Deuterated aminocyclohexyl ether compounds and processes for preparing same

ABSTRACT

This invention is directed to deuterated aminocyclohexyl ether compounds and processes for preparing same and methods of using same.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of PCT Patent Application No. PCT/US06/23668, filed Jun. 15, 2006, now pending, which claims priority to U.S. Provisional Patent Application No. 60/690,989, filed Jun. 15, 2005, and U.S. Provisional Patent Application No. 60/748,248, filed Dec. 7, 2005, which applications are incorporated herein by reference in their entireties.

This application is also a continuation-in-part of PCT Patent Application No. PCT/US05/11124, filed Mar. 31, 2005, now pending, which claims priority to U.S. Provisional Patent Application No. 60/559,405, filed Apr. 1, 2004, and U.S. Provisional Patent Application No. 60/586,992, filed Jul. 8, 2004, which applications are incorporated herein by reference in their entireties.

This application also claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 60/748,248, filed Dec. 7, 2005; of U.S. which application is incorporated herein by reference in its entirety.

FIELD OF INVENTION

The present invention is generally directed towards deuterated aminocyclohexyl ether compounds and methods for their preparation. In particular, this invention is directed to deuterated-trans-(1R,2R)-aminocyclohexyl ether compounds, deuterated-trans-(1S,2S)-aminocyclohexyl ether compounds, deuterated cis-(1R,2S)-aminocyclohexyl ether compounds, and deuterated cis-(1S,2R)aminocyclohexyl ether compounds, as well as various intermediates, substrates and stereoisomers and methods for their preparation. The deuterated compounds of the invention are useful as standards in determining the biological efficacy of the corresponding non-deuterated compounds. The deuterated compounds of the invention are also useful in treating arrhythmia in humans.

BACKGROUND OF THE INVENTION

Deuterated drugs are widely used in studies of metabolism of drugs and toxic substances in humans and other animals. The deuterated forms of drugs often have different actions than the protonated forms. Some deuterated drugs show different transport processes. Most are more resistant to metabolic changes, especially those changes mediated by cytochrome P450 systems. Deuteration may also change the pathway of drug metabolism (metabolic switching). Changed metabolism may lead to increased duration of action and lower toxicity. It may also lead to lower activity, if the drug is normally changed to the active form in vivo. Deuteration can also lower the genotoxicity of the anticancer drug tamoxifen and other compounds. Deuteration increases effectiveness of long-chain fatty acids and fluoro-D-phenylalanine by preventing their breakdown by target microorganisms.

Deuterium (D) is a nonradioactive isotope which contains one additional neutron than the normally abundant isotope of hydrogen which does not contain any neutrons. Deuterium behaves similarly to ordinary hydrogen, but it can be distinguished from ordinary hydrogen by its mass using mass spectrometry or infrared spectrometry. Consequently, deuterated compounds have been long used in pharmaceutical research to investigate the in vivo metabolic fate of the compounds by evaluation of the mechanism of action and metabolic-pathway of the non deuterated parent compound. Such metabolic studies are important in the design of safe, effective therapeutic drugs.

Incorporation of deuterium for a hydrogen atom in a drug can give rise to an isotope effect that can alter the pharmacokinetics of the drug. This effect is usually insignificant if the label is placed in a molecule at the metabolically inert position of the molecule. For instance, deuteration, as exemplified by deuterated Rapamycin (see U.S. Pat. No. 6,503,921), Cyclosporine (see U.S. Pat. No. 6,613,739) or Nifedipine (see U.S. Pat. No. 5,846,514) has been reported to alter the pharmacokinetics of a drug. Forster et al. (Isotechnica, AB) have shown that deuteration can enhance duration of action.

Deuterium-labeling of a drug can alter its physico-chemical properties such as pKa and lipid solubility. These changes may influence the fate of the drug at different steps along its passage through the body. Absorption, distribution, metabolism or excretion can be changed. Absorption and distribution are processes that depend primarily on the molecular size and the lipophilicity of the substance.

Drug metabolism can give rise to large isotopic effect if the breaking of a chemical bond to a deuterium atom is the rate limiting step in the process. While some of the physical properties of a deuterium-labeled molecule are different from those of the unlabeled one, the chemical and biological properties are the same, with one important exception: because of the increased mass of the heavy isotope, any bond involving the heavy isotope and another atom will be stronger than the same bond between the light isotope and that atom. In any reaction in which the breaking of this bond is the rate limiting step, the reaction will proceed slower for the molecule with the heavy isotope due to kinetic isotope effect. A reaction involving breaking a C-D bond can be up to 700 percent slower than a similar reaction involving breaking a C—H bond.

More caution has to be observed when using deuterium-labeled drugs. If the C-D bored is not involved in any of the steps leading to the metabolite, there may not be any effect to alter the behavior of the drug. If deuterium is placed at a site involved in the metabolism of a drug, an isotope effect will be observed only if breaking of the C-D bond is the rate limiting step. There are evidences to suggest that whenever cleavage of an aliphatic C—H bond occurs, usually by oxidation catalyzed by a mixed-function oxidase, replacement of the hydrogen by deuterium will lead to observable isotope effect. It is also important to understand that the incorporation of deuterium at the site of metabolism slows its rate to the point where another metabolite produced by attack at a carbon atom not substituted by deuterium becomes the major pathway by a process called “metabolic switching”.

It is also observed that one of the most important metabolic pathways of compounds containing aromatic systems is hydroxylation leading to a phenolic group in the 3 or 4 position to carbon substituents. Although this pathway involves cleavage of the C—H bond, it is often not accompanied by an isotope effect, because the cleavage of this bond is mostly not involved in the rate-limiting step. The substitution of hydrogen by deuterium at the stereo center will induce a greater effect on the activity of the drug.

Clinically relevant questions with respect to deuterium-labeled drugs include the toxicity of the drug and its metabolite derivatives, the changes in distribution or elimination (enzyme induction), lipophilicity which will have an effect on absorption of the drug. Replacement of hydrogen by deuterium at the site involving the metabolic reaction will lead to increased toxicity of the drug. Replacement of hydrogen by deuterium at the aliphatic carbons will have an isotopic effect to a larger extent. Deuterium placed at an aromatic carbon atom, which will be the site of hydroxylation, may lead to an observable isotope effect, although this is less often the case than with aliphatic carbons. In few cases, such as in penicillin, the substitution on the aromatic ring will induce the restriction of rotation of the ring around the C—C bond leading to a favorable stereo-specific situation to enhance the activity of the drug.

Side-effects with acute deuterium dosing have been shown to be transitory with no demonstrated evidence of permanent deleterious action. The threshold of deuterium toxicity has been defined in animals and is far in excess of concentrations conceivably used in human studies. The possibility that deuterium may have additional beneficial pharmacological applications can therefore not be excluded.

PCT Published Patent Application, WO 2004/099137 discloses a class of aminocyclohexyl ether compounds as being useful in the treatment of arrhythmias. One class of compounds disclosed therein are particularly effective in the treatment and/or prevention of arrhythmia, particularly atrial fibrillation.

There exists, therefore, a need to prepare deuterated compounds which can be used, inter alia, as standards or tracer molecules in biological or bioanalytical assays in order to determine the biological effectiveness and metabolic pathway for a class of compounds disclosed in PCT Published Patent Application WO 99/50225.

SUMMARY OF THE INVENTION

In one aspect, this invention is directed to compounds of formula (I):

wherein:

-   R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R¹¹, R¹², R¹³, R¹⁴, R¹⁵ and R¹⁶ are     each independently hydrogen or deuterium; -   R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; and -   at least one deuterium is present; -   as an isolated stereoisomer or as a mixture of stereoisomers; -   or a pharmaceutically acceptable salt thereof.

In another aspect, this invention is directed to compounds of formula (I), as described above, wherein:

-   R¹ and R² are both hydrogen or are both deuterium; -   R³ and R⁴ are both hydrogen or are both deuterium; -   R⁵ and R⁶ are both hydrogen or are both deuterium; -   R⁷ and R⁸ are both hydrogen or are both deuterium; -   R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; -   R¹¹ is hydrogen or deuterium; -   R¹² and R¹³ are both hydrogen or are both deuterium; and -   R¹⁴, R¹⁵ and R¹⁶ are each hydrogen; -   wherein at least one of the following applies:     -   a) R¹ and R² are both deuterium;     -   b) R³ and R⁴ are both deuterium;     -   c) R⁵ and R⁶ are both deuterium;     -   d) R⁷ and R⁸ are both deuterium;     -   e) R⁹ is —OCD₃;     -   f) R¹⁰ is —OCD₃;     -   g) R¹¹ is deuterium; or     -   h) R¹² and R¹³ are both deuterium; -   as an isolated stereoisomer or as a mixture of stereoisomers; -   or a pharmaceutically acceptable salt thereof.

In another aspect, this invention is directed to pharmaceutical compositions comprising a pharmaceutically acceptable excipient and a compound of formula (I), as described above, as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof.

In another aspect, this invention is directed to methods of treating arrhythmia in a human, wherein the methods comprise administering to the human in need thereof a therapeutically effective amount of a compound of formula (I), as described above, as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof.

In another aspect, this invention is directed to methods of preparing compounds of formula (I), as described above, where R¹⁴, R¹⁵ and R¹⁶ are each hydrogen, as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof.

In another aspect, this invention is directed to methods of determining the concentration of a compound in a biological matrix, wherein the method comprises contacting a compound of formula (I), as described above, where R¹⁴, R¹⁵ and R¹⁶ are each hydrogen, as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof, with a biological matrix containing a compound of formula (1):

wherein each R^(9a) and R^(10a) are independently hydroxy or methoxy; as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof; and determining the concentration of the compound of formula (1) in the biological matrix.

In another aspect, this invention is directed to compounds of formula (II):

wherein:

-   R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R¹¹, R¹² and R¹³ are each     independently hydrogen or deuterium; -   R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; and -   at least one deuterium is present; -   as an isolated stereoisomer or as a mixture of stereoisomers; -   or a pharmaceutically acceptable salt thereof.

In another aspect, this invention is directed to compounds of formula (II) described above, wherein:

-   R¹ and R² are both hydrogen or are both deuterium; -   R³ and R⁴ are both hydrogen or are both deuterium; -   R⁵ and R⁶ are both hydrogen or are both deuterium; -   R⁷ and R⁸ are both hydrogen or are both deuterium; -   R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; -   R¹¹ is hydrogen or deuterium; and -   R¹² and R¹³ are both hydrogen or are both deuterium; -   wherein at least one of the following applies:     -   a) R¹ and R² are both deuterium;     -   b) R³ and R⁴ are both deuterium;     -   c) R⁵ and R⁶ are both deuterium;     -   d) R⁷ and R⁸ are both deuterium;     -   e) R⁹ is —OCD₃;     -   f) R¹⁰ is —OCD₃;     -   g) R¹¹ is deuterium; or     -   h) R¹² and R¹³ are both deuterium; -   as an isolated stereoisomer or as a mixture of stereoisomers; -   or a pharmaceutically acceptable salt thereof.

In another aspect, this invention is directed to pharmaceutical compositions comprising a pharmaceutically acceptable excipient and a compound of formula (II), as described above, as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof.

In another aspect, this invention is directed to methods of treating arrhythmia in a human, wherein the methods comprise administering to the human in need thereof a therapeutically effective amount of a compound of formula (II), as described above, as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof.

In another aspect, this invention is directed to methods of preparing compounds of formula (II), as described above, as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof.

In another aspect, this invention is directed to methods of determining the concentration of a compound in a biological matrix, wherein the method comprises contacting a compound of formula (II), as described above, as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof, with a biological matrix containing a compound of formula (2):

wherein each R^(9a) and R^(10a) are independently hydroxy or methoxy; as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof; and determining the concentration of the compound of formula (2) in the biological matrix.

These and other aspects of the invention will be apparent upon reference to the following detailed description. To this end, various references are set forth herein which describe in more detail certain background information, procedures, compounds and/or compositions, and are each hereby incorporated by reference in their entirety.

DETAILED DESCRIPTION OF THE INVENTION

An understanding of the present invention may be aided by reference to the following explanation of conventions used herein and definitions:

The compounds of formula (I) and the compounds of formula (II) have an ether oxygen atom at position 1 of a cyclohexane ring, and an amine nitrogen atom at position 2 of the cyclohexane ring, with other positions numbered in corresponding order as shown below in Structure (Aa) and Structure (Ab), respectively, below:

The bonds from the cyclohexane ring to the 1-oxygen and 2-nitrogen atoms in the Structure (Aa) above are disposed in the trans relationship. Therefore, the stereochemistry of the amine and ether substituents of the cyclohexane ring in Structure (Aa) is (1R,2R)-trans or (1S,2S)-trans. The bonds from the cyclohexane ring to the 1-oxygen and 2-nitrogen atoms in the Structure (Ab) above are disposed in the cis relationship. Therefore, the stereochemistry of the amine and ether substituents of the cyclohexane ring in Structure (Ab) is (1R,2S)-cis or (1R,2S)-cis.

Following the standard chemical literature description practice and as used in this specification, a solid full bond, as illustrated above in Structure (Aa) and a dashed full bond, as illustrated above in Structure (Aa), means that the substituents, in this case the amine and ether substituents, are in a trans-configuration with respect to the plane of the ring.

Following the standard chemical literature description practice and as used in this specification, a solid full bond, as illustrated above in Structure (Ab) and a solid full bond, as illustrated above in Structure (Ab), means that the substituents, in this case the amine and ether substituents, are in a cis-configuration with respect to the plane of the ring.

Following the standard chemical literature description practice and as used in this specification, a full wedge bond, as exemplified below in Structure (Ac), means that the substituent bonded to the ring by this bond, in this case the ether substituent, is above the ring plane as illustrated on the page in a two dimensional representation, and a dashed wedge bond, as exemplified below in Structure (Ac), means that the substituent bonded to the ring by this bond, in this case the amine substituent, is below the ring plane as shown on the page in a two dimensional representation. In contrast, two full wedge bonds, as exemplified below in Structure (Ad), means that both substituents bonded to the ring by these bonds, in this case both the ether and the amino substituent, are above the ring plane as illustrated on the page in a two dimensional representation:

In a similar manner, as exemplified below in Structure (Ae), the ether substituent is below the ring plane and the amino substituent is above the ring plane, as shown on the page in a two dimensional representation. In contrast, as exemplified below in Structure (Af), both the ether and the amino substituent are below the ring plane as illustrated on the page in a two dimensional representation:

Following the standard chemical literature description practice and as used in this specification, a wavy bond, as illustrated below in the compound of formula (B), indicates that the substituent, in this case the —OR substituent, is either below the plane of the ring or above the plane of the ring:

As indicated above, the compounds of the present invention contain at least two asymmetric carbon atoms and thus exist as enantiomers and diastereoisomers. For the present invention, the words diastereomer and diastereoisomer and related terms are equivalent and interchangeable. Unless otherwise indicated, the present invention includes all enantiomeric and diastereoisomeric forms of the aminocyclohexyl ether compounds of formula (I) and formula (II). Pure stereoisomers, mixtures of enantiomers and/or diastereoisomers, and mixtures of different compounds of the invention are included within the present invention. Thus, compounds of formula (I) and compounds of formula (II) may occur as racemates, diastereomeric mixtures and as individual diastereoisomers, or enantiomers, unless a specific stereoisomer enantiomer or diastereoisomer is identified, with all isomeric forms being included in the present invention. For the present invention, a racemate or diastereomeric mixture does not imply a 50:50 mixture of stereoisomers only. Other enantiomerically or diastereomerically enriched mixtures of varying ratios of stereoisomers are also contemplated. Unless otherwise noted, the phrase “stereoisomerically substantially pure” generally refers to those asymmetric carbon atoms that are described or illustrated in the structural formulae for that compound.

The definition of stereoisomeric purity (or optical purity or chiral purity) and related terminology and their methods of determination (e.g., Optical rotation, circular dichroism etc.) are well known in the art (see e.g., E. L. Eliel and S. H. Wilen, in Stereochemistry of Organic Compounds; John Wiley & Sons: New York, 1994; and references cited therein). The phrase “stereoisomerically substantially pure” generally refers to the enrichment of one of the stereoisomers (e.g., enantiomers or diastereoisomers) over the other stereoisomers in a sample, leading to chiral enrichment and increase in optical rotation activity of the sample. Enantiomer is one of a pair of molecular species that are mirror images of each other and not superimposable. They are “mirror-image” stereoisomers. Diastereoisomers generally refer to stereoisomers not related as mirror-images. Enantiomeric excess (ee) and diastereoisomeric excess (de) are terms generally used to refer the stereoisomeric purity (or optical purity or chiral purity) of a sample of the compound of interest. Their definition and methods of determination are well known in the art and can be found e.g., in E. L. Eliel and S. H. Wilen, in Stereochemistry of Organic Compounds; John Wiley & Sons: New York, 1994; and references cited therein. “Stereoselectively making” refers to preparing the compound having enantiomeric excess (ee) or diastereoisomeric excess (de).

For the present invention, enantiomeric excess (ee) or diastereoisomeric excess (de) in the range of about 50% to about 100% is contemplated. A preferred range of enantiomeric excess (ee) or diastereoisomeric excess (de) is about 60% to about 100%. Another preferred range of enantiomeric excess (ee) or diastereoisomeric excess (de) is about 70% to about 100%. A more preferred range of enantiomeric excess (ee) or diastereoisomeric excess (de) is about 80% to about 100%. Another more preferred range of enantiomeric excess (ee) or diastereoisomeric excess (de) is about 85% to about 100%. An even more preferred range of enantiomeric excess (ee) or diastereoisomeric excess (de) is about 90% to about 100%. Another even more preferred range of enantiomeric excess (ee) or diastereoisomeric excess (de) is about 95% to about 100%. It is understood that the phrase “about 50% to about 100%” includes but is not limited to all the possible percentage numbers and fractions of a number from 50% to 100%. Similarly, the phrase “about 60% to about 100%” includes but is not limited to all the possible percentage numbers and fractions of a number from 60% to 100%; the phrase “about 70% to about 100%” includes but is not limited to all the possible percentage numbers and fractions of a number from 70% to 100%; the phrase “about 80% to about 100%” includes but is not limited to all the possible percentage numbers and fractions of a number from 80% to 100%; the phrase “about 85% to about 100%” includes all but is not limited to the possible percentage numbers and fractions of a number from 85% to 100%; the phrase “about 90% to about 100%” includes but is not limited to all the possible percentage numbers and fractions of a number from 90% to 100%; the phrase “about 95% to about 100%” includes all but is not limited to the possible percentage numbers and fractions of a number from 95% to 100%.

As an example, and in no way limiting the generality of the above, a compound of formula (I):

as described above in the Summary of the Invention, includes at least three chiral centers (the cyclohexyl carbon bonded to the oxygen at the 1 position, the cyclohexyl carbon bonded to the nitrogen at the 2 position, and the pyrrolidinyl carbon bonded to the hydroxyl at the 3 position of the pyrrolidinyl) and therefore has at least four separate stereoisomers, which are (1R,2R)-2-[(3R)-hydroxypyrrolidinyl]-1-(substituted phenethoxy)cyclohexane; (1R,2R)-2-[(3S)-hydroxypyrrolidinyl]-1-(substituted phenethoxy)cyclohexane; (1S,2S)-2-[(3R)-hydroxypyrrolidinyl]-1-(substituted phenethoxy)cyclohexane; and (1S,2S)-2-[(3S)-hydroxypyrrolidinyl]-1-(substituted phenethoxy)cyclohexane; and, unless the context make plain otherwise as used in this specification, for example, a compound of formula (I) refers to a composition that includes a component that is either one of the possible pure enantiomeric or diastereoisomeric forms of the indicated compound or is a mixture of any two or more of the pure enantiomeric or diastereoisomeric forms, where the mixture can include any number of the enantiomeric or diastereoisomeric forms in any ratio.

Similarly, a compound of formula (II):

as described above in the Summary of the Invention, also includes at least three chiral centers and therefore has at least four separate stereoisomers, which are (1S,2R)-2-[(3R)-hydroxypyrrolidinyl]-1-(substituted phenethoxy)cyclohexane; (1S,2R)-2-[(3S)-hydroxypyrrolidinyl]-1-(substituted phenethoxy)cyclohexane; (1S,2R)-2-[(3R)-hydroxypyrrolidinyl]-1-(substituted phenethoxy)cyclohexane; and (1S,2R)-2-[(3S)-hydroxypyrrolidinyl]-1-(substituted phenethoxy)cyclohexane; and, unless the context make plain otherwise as used in this specification, for example, a compound of formula (II) refers to a composition that includes a component that is either one of the possible pure enantiomeric or diastereoisomeric forms of the indicated compound or is a mixture of any two or more of the pure enantiomeric or diastereoisomeric forms, where the mixture can include any number of the enantiomeric or diastereoisomeric forms in any ratio.

Certain chemical groups named herein are preceded by the shorthand notation “C_(x)-C_(y)” where x and y indicate the lower and upper, respectively, number of carbon atoms to be found in the indicated chemical group. For example; C₁-C₈acyl describes an acyl group, as defined below, having a total of 1 to 8 carbon atoms. Occasionally, certain chemical groups named herein are preceded by the shorthand notation “C_(z)” where z indicates the total number of carbons to be found in the indicated chemical group. The total number of carbons in the shorthand notation does not include carbons that may exist in substituents of the group described.

In accordance with the present invention and as used herein, the following terms are defined to have following meanings, unless explicitly stated otherwise:

“Acid addition salts” generally refer to but are not limited to those salts which retain the biological effectiveness and properties of the free bases and which are not biologically or otherwise undesirable, formed with inorganic acids such as but not limited to hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid and the like, or acceptable Lewis acids, or organic acids such as but not limited to acetic acid, propionic acid, glycolic acid, pyruvic acid, oxalic acid, maleic acid, malonic acid, succinic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, cinnamic acid, mandelic acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, salicylic acid and the like, and include but not limited to those described in for example: “Handbook of Pharmaceutical Salts, Properties, Selection, and Use”, P. Heinrich Stahl and Camille G. Wermuth (Eds.), Published by VHCA (Switzerland) and Wiley-VCH (FRG), 2002.

“Acyl” refers to branched or unbranched hydrocarbon fragments terminated by a carbonyl —(C═O)— group containing the specified number of carbon atoms. Examples include acetyl (Ac) [CH₃C(═O)—, a C₂acyl] and propionyl [CH₃CH₂C(═O)—, a C₃acyl].

“Biological matrix” refers to an environment that may or may not be isolated from a warm-blooded animal. Non-limiting examples of biological matrices are: urine, feces, blood, serum, plasma, saliva, perspiration, tissue fluid, cellular cytoplasm, hepatocytes, microsomes, S9 fractions, tissues, such as muscle tissue, hepatic tissue, cardiac tissue, renal tissue and other bodily environments and/or matrices of a warm-blooded animal, preferably a human. A biological matrix may be present in solution or in solid form or a mixture thereof and may be present in or as part of a living organism or may be isolated from a living organism such that it forms a sample therefrom.

“Pharmaceutically acceptable excipients” for therapeutic use are well known in the pharmaceutical art, and are described, for example, in Remingtons Pharmaceutical Sciences, Mack Publishing Co. (A. R. Gennaro edit. 1985). For example, sterile saline and phosphate-buffered saline at physiological pH may be used. Preservatives, stabilizers, dyes and even flavoring agents may be provided in the pharmaceutical composition. For example, sodium benzoate, sorbic acid and esters of p-hydroxybenzoic acid may be added as preservatives. In addition, antioxidants and suspending agents may be used.

“Pharmaceutically acceptable salt” refers to salts of the compounds of the present invention derived from the combination of such compounds and a pharmaceutically acceptable organic or inorganic acid (acid addition salts) or a pharmaceutically acceptable organic or inorganic base (base addition salts) which retain the biological effectiveness and properties of the compounds of the present invention and which are not biologically or otherwise undesirable. Examples of pharmaceutically acceptable salts include, but are not limited to, those described in, for example, “Handbook of Pharmaceutical Salts, Properties, Selection, and Use”, P. Heinrich Stahl and Camille G. Wermuth (Eds.), Published by VHCA (Switzerland) and Wiley-VCH (FRG), 2002. The compounds of the present invention may be used in either the free base or salt forms, with both forms being considered as being within the scope of the present invention.

The “therapeutically effective amount” of a compound of the present invention will depend on the route of administration, the type of warm-blooded animal being treated, and the physical characteristics of the specific warm-blooded animal under consideration. These factors and their relationship to determining this amount are well known to skilled practitioners in the medical arts. This amount and the method of administration can be tailored to achieve optimal efficacy but will depend on such factors as weight, diet, concurrent medication and other factors which those skilled in the medical arts will recognize.

Compositions described herein as comprising a compound of the present invention encompass compositions that may contain more than one compound of the present invention.

The chemical naming protocol and structure diagrams used herein are a modified form of the I.U.P.A.C. nomenclature system wherein the compounds of the invention are named herein as derivatives of the central core structure, i.e., the cyclohexane structure. Thus, a compound of formula (I) wherein R¹, R², R³, R⁴, R⁵ and R⁶ are each deuterium and R⁷, R⁸, R¹¹, R¹² and R¹³ are each hydrogen and R⁹ is methoxy and R¹⁰ is —OCD₃, and R¹⁴, R¹⁵, and R¹⁶ are each hydrogen, i.e., a compound of the following formula:

is named herein as (1R,2R/1S,2S)-2-[(3R/3S)-hydroxy-2,2,5,5-d₄-pyrrolidinyl]-1-(3-methoxy-4-d₃-methoxyphen-1,1-d₂-ethoxy)cyclohexane.

Utility of the Compounds of the Invention

Compounds of formula (I) and compounds of formula (II) may be used as standards to determine the concentration of the corresponding non-deuterated compounds in various biological matrices (such as plasma, serum, and urine).

The corresponding non-deuterated compounds are disclosed in PCT Published Patent Application, WO 2004/099137 and are useful in treating, inter alia, arrhythmia, particularly, atrial fibrillation and/or flutter. Of particular interest is the use of the compounds of the invention to determine the concentration of the following compounds of formula (1) and/or compounds of formula (2) in various biological matrices:

where each R^(9a) and each R^(10a) are independently hydroxy or methoxy, as isolated stereoisomers or as mixtures of stereoisomers; or pharmaceutically acceptable salts thereof. The stereochemistry at position 1 and 2 of the cyclohexyl group in compounds of formula (1) and formula (2) is depicted in the same manner as described herein for compounds of formula (I) and formula (II).

The use of the compounds of the invention as standards allows for the compensation of any instrumental or sample preparation error in the bioanalysis of the compounds of formula (1) and the compounds of formula (2) present in biological matrices. The compounds of the invention corresponding to the compounds of formula (1) and the compounds of formula (2), as set forth above, behave in the same manner as the compounds of formula (1) and compounds of formula (2) in such assays. However, the compounds of the invention can be differentiated from the compounds of formula (1) or the compounds of formula (2) in such assays through mass spectrometry due to the presence of one or more deuterium atoms thereon.

Compounds of formula (I) and compounds of formula (II) may also be used as probes in assays for metabolic profiling, for example in cytochrome p450 enzyme assays, such as CYP2D6.

The compounds of the invention are also useful as pharmaceutical agents in the treatment of arrhythmia, particularly atrial fibrillation and/or flutter, in the same manner as described for the corresponding non-deuterated compounds disclosed in PCT Published Patent Application, WO 2004/099137.

Pharmaceutical Compositions of the Invention and Administration

For the purposes of administering a compound of the invention to a human to treat arrhythmia, the compounds of the invention, as isolated stereoisomers or as mixtures of stereoisomers; or pharmaceutically acceptable salts thereof, may be formulated as pharmaceutical compositions. Pharmaceutical compositions of the present invention comprise a compound of the invention, as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable excipient, carrier and/or diluent. The compound of the invention, as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof, is present in the composition in an amount sufficient to effect treatment of arrhythmia in a human, i.e., in a therapeutically effective amount.

Pharmaceutically acceptable excipients, carriers and/or diluents are familiar to those skilled in the art. For compositions formulated as liquid solutions, acceptable carriers and/or diluents include saline and sterile water, and may optionally include antioxidants, buffers, bacteriostats and other common additives. The pharmaceutical compositions of the invention can be prepared by combining a compound of the invention, as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof, with an appropriate pharmaceutically acceptable carrier, diluent or excipient, and may be formulated into preparations in solid, semi-solid, liquid or gaseous forms, such as tablets, capsules, powders, granules, ointments, solutions, suppositories, injections, inhalants, gels, microspheres, and aerosols. These compositions may also contain dispersing and surface active agents, binders, and lubricants. One skilled in this art may further formulate the compound of the invention, as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof, in an appropriate manner, and in accordance with accepted practices, such as those disclosed in Remington's Pharmaceutical Sciences, Gennaro, Ed., Mack Publishing Co., Easton, Pa. 1990.

Typical routes of administering the pharmaceutical compositions of the invention include, without limitation, oral, topical, transdermal, inhalation, parenteral, sublingual, buccal, rectal, vaginal, and intranasal. The term parenteral as used herein includes subcutaneous injections, intravenous, intramuscular, intrasternal injection or infusion techniques. Pharmaceutical compositions of the invention are formulated so as to allow a compound of the invention, as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof, contained therein to be bioavailable upon administration of the composition to a human.

The compounds of the invention, as isolated stereoisomers or as mixtures of stereoisomers, or pharmaceutically acceptable salts thereof, are administered in a therapeutically effective amount, which will vary depending upon a variety of factors including the activity of the specific compound employed; the metabolic stability and length of action of the compound; the age, body weight, general health, sex, and diet of the person to which the compound and/or composition of the invention is administered; the mode and time of administration; the rate of excretion; the drug combination; and the severity of the condition to be treated. Generally, a therapeutically effective daily dose is (for a 70 kg mammal) from about 0.001 mg/kg (i.e., 0.7 mg) to about 100 mg/kg (i.e., 7.0 gm); preferably a therapeutically effective dose is (for a 70 kg mammal) from about 0.01 mg/kg (i.e., 7 mg) to about 50 mg/kg (i.e., 3.5 gm); more preferably a therapeutically effective dose is (for a 70 kg mammal) from about 1 mg/kg (i.e., 70 mg) to about 25 mg/kg (i.e., 1.75 gm).

Compounds of the invention, as isolated stereoisomers or as mixtures of stereoisomers, or pharmaceutically acceptable salts thereof, may also be administered simultaneously with, prior to, or after administration of one or more other therapeutic agents. Such combination therapy includes administration of a single pharmaceutical dosage formulation which contains a compound of the invention and one or more additional active agents, as well as administration of the compound of the invention and each active agent in its own separate pharmaceutical dosage formulation. For example, a compound of the invention, as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof, and the other active agent can be administered to the human together in a single oral dosage composition such as a tablet or capsule, or each agent can be administered to the human in separate oral dosage formulations. Where separate dosage formulations are used, the compounds of the invention and one or more additional active agents can be administered to the human at essentially the same time, i.e., concurrently, or at separately staggered times, i.e., sequentially; combination therapy is understood to include all these regimens.

Embodiments of the Invention

Of the various aspects of the invention, as set forth above in the Summary of the Invention, certain embodiments are preferred:

One embodiment are the compounds of formula (I) wherein:

-   R¹ and R² are both hydrogen or are both deuterium; -   R³ and R⁴ are both hydrogen or are both deuterium; -   R⁵ and R⁶ are both hydrogen or are both deuterium; -   R⁷ and R⁸ are both hydrogen or are both deuterium; -   R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; -   R¹¹ is hydrogen or deuterium; -   R¹² and R¹³ are both hydrogen or are both deuterium; and -   R¹⁴, R¹⁵, and R¹⁶ are all hydrogen or all deuterium.

Another embodiment are the compounds of formula (I) wherein:

-   R¹ and R² are both hydrogen or are both deuterium; -   R³ and R⁴ are both hydrogen or are both deuterium; -   R⁵ and R⁶ are both deuterium; -   R⁷ and R⁸ are both hydrogen or are both deuterium; -   R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; -   R¹¹ is hydrogen or deuterium; -   R¹² and R¹³ are both hydrogen or are both deuterium; and -   R¹⁴, R¹⁵, and R¹⁶ are all hydrogen or all deuterium.

Another embodiment are the compounds of formula (I) wherein:

-   R¹ and R² are both hydrogen or are both deuterium; -   R³ and R⁴ are both hydrogen or are both deuterium; -   R⁵ and R⁶ are both hydrogen or are both deuterium; -   R⁷ and R⁸ are both deuterium; -   R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; -   R¹¹ is hydrogen or deuterium; -   R¹² and R¹³ are both hydrogen or are both deuterium; and -   R¹⁴, R¹⁵, and R¹⁶ are all hydrogen or all deuterium.

Another embodiment are the compounds of formula (I) wherein:

-   R¹ and R² are both deuterium; -   R³ and R⁴ are both deuterium; -   R⁵ and R⁶ are both hydrogen or are both deuterium; -   R⁷ and R⁸ are both hydrogen or are both deuterium; -   R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; -   R¹¹ is hydrogen or deuterium; -   R¹² and R¹³ are both hydrogen or are both deuterium; and -   R¹⁴, R¹⁵, and R¹⁶ are all hydrogen or all deuterium.

Another embodiment are the compounds of formula (I) wherein:

-   R¹ and R² are both hydrogen or are both deuterium; -   R³ and R⁴ are both hydrogen or are both deuterium; -   R⁵ and R⁶ are both hydrogen or are both deuterium; -   R⁷ and R⁸ are both hydrogen or are both deuterium; -   R⁹ is —OCD₃; -   R¹⁰ is hydroxy, methoxy or —OCD₃; -   R¹¹ is hydrogen or deuterium; -   R¹² and R¹³ are both hydrogen or are both deuterium; and -   R¹⁴, R¹⁵, and R¹⁶ are all hydrogen or all deuterium.

Another embodiment are the compounds of formula (I) wherein:

-   R¹ and R² are both hydrogen or are both deuterium; -   R³ and R⁴ are both hydrogen or are both deuterium; -   R⁵ and R⁶ are both hydrogen or are both deuterium; -   R⁷ and R⁸ are both hydrogen or are both deuterium; -   R⁹ is hydroxy, methoxy or —OCD₃; -   R¹⁰ is —OCD₃; -   R¹¹ is hydrogen or deuterium; -   R¹² and R¹³ are both hydrogen or are both deuterium; and -   R¹⁴, R¹⁵, and R¹⁶ are all hydrogen or all deuterium.

Another embodiment are the compounds of formula (I) wherein:

-   R¹ and R² are both hydrogen or are both deuterium; -   R³ and R⁴ are both hydrogen or are both deuterium; -   R⁵ and R⁶ are both hydrogen or are both deuterium; -   R⁷ and R⁸ are both hydrogen or are both deuterium; -   R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; -   R¹¹ is deuterium; -   R¹² and R¹³ are both hydrogen or are both deuterium; and -   R¹⁴, R¹⁵, and R¹⁶ are all hydrogen or all deuterium.

Another embodiment are the compounds of formula (I) wherein:

-   R¹ and R² are both hydrogen or are both deuterium; -   R³ and R⁴ are both hydrogen or are both deuterium; -   R⁵ and R⁶ are both hydrogen or are both deuterium; -   R⁷ and R⁸ are both hydrogen or are both deuterium; -   R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; -   R¹¹ is hydrogen or deuterium; -   R¹² and R¹³ are both deuterium; and -   R¹⁴, R¹⁵, and R¹⁶ are all hydrogen or all deuterium.

Another embodiment are the compounds of formula (I):

wherein:

-   R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R¹¹, R¹², R¹³, R¹⁴, R¹⁵ and R¹⁶ are     each independently hydrogen or deuterium; -   R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; -   at least one deuterium is present and when R¹⁰ is —OCD₃, then at     least one of R¹, R², R³, R⁴, R⁵, R⁶, R⁶, R⁸, R¹² and R¹³ is     deuterium; -   and when R⁵, R⁶, R⁷, and R⁸ are deuterium, R⁹ and R¹⁰ are both     —OCH₃, then at least one of R³, R⁴, R¹² or R¹³ is deuterium; -   and when R¹⁴, R¹⁵, and R¹⁶ are each deuterium, at least one of R¹,     R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R¹¹, R¹² and R¹³ is deuterium; -   as an isolated stereoisomer or as a mixture of stereoisomers; -   or a pharmaceutically acceptable salt thereof.

Another embodiment are the compounds of formula (I) which do not include the following compounds:

-   -   or pharmaceutically acceptable salts thereof.

Another embodiment of the invention are the compounds of formula (II) wherein:

-   R¹ and R² are both hydrogen or are both deuterium; -   R³ and R⁴ are both hydrogen or are both deuterium; -   R⁵ and R⁶ are both hydrogen or are both deuterium; -   R⁷ and R⁸ are both hydrogen or are both deuterium; -   R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; -   R¹¹ is hydrogen or deuterium; and -   R¹² and R¹³ are both hydrogen or are both deuterium.

Another embodiment are the compounds of formula (II) wherein:

-   R¹ and R² are both hydrogen or are both deuterium; -   R³ and R⁴ are both hydrogen or are both deuterium; -   R⁵ and R⁶ are both deuterium; -   R⁷ and R⁸ are both hydrogen or are both deuterium; -   R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; -   R¹¹ is hydrogen or deuterium; and -   R¹² and R¹³ are both hydrogen or are both deuterium.

Another embodiment are the compounds of formula (II) wherein:

-   R¹ and R² are both hydrogen or are both deuterium; -   R³ and R⁴ are both hydrogen or are both deuterium; -   R⁵ and R⁶ are both hydrogen or are both deuterium; -   R⁷ and R⁸ are both deuterium; -   R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; -   R¹¹ is hydrogen or deuterium; and -   R¹² and R¹³ are both hydrogen or are both deuterium;

Another embodiment are the compounds of formula (II) wherein:

-   R¹ and R² are both deuterium; -   R³ and R⁴ are both deuterium; -   R⁵ and R⁶ are both hydrogen or are both deuterium; -   R⁷ and R⁸ are both hydrogen or are both deuterium; -   R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; -   R¹¹ is hydrogen or deuterium; and -   R¹² and R¹³ are both hydrogen or are both deuterium.

Another embodiment are the compounds of formula (II) wherein:

-   R¹ and R² are both hydrogen or are both deuterium; -   R³ and R⁴ are both hydrogen or are both deuterium; -   R⁵ and R⁶ are both hydrogen or are both deuterium; -   R⁷ and R⁸ are both hydrogen or are both deuterium; -   R⁹ is —OCD₃; -   R¹⁰ is hydroxy, methoxy or —OCD₃; -   R¹¹ is hydrogen or deuterium; and -   R¹² and R¹³ are both hydrogen or are both deuterium.

Another embodiment are the compounds of formula (II) wherein:

-   R¹ and R² are both hydrogen or are both deuterium; -   R³ and R⁴ are both hydrogen or are both deuterium; -   R⁵ and R⁶ are both hydrogen or are both deuterium; -   R⁷ and R⁸ are both hydrogen or are both deuterium; -   R⁹ is hydroxy, methoxy or —OCD₃; -   R¹⁰ is —OCD₃; -   R¹¹ is hydrogen or deuterium; and -   R¹² and R¹³ are both hydrogen or are both deuterium.

Another embodiment are the compounds of formula (II) wherein:

-   R¹ and R² are both hydrogen or are both deuterium; -   R³ and R⁴ are both hydrogen or are both deuterium; -   R⁵ and R⁶ are both hydrogen or are both deuterium; -   R⁷ and R⁸ are both hydrogen or are both deuterium; -   R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; -   R¹¹ is deuterium; and -   R¹² and R¹³ are both hydrogen or are both deuterium.

Another embodiment are the compounds of formula (II) wherein:

-   R¹ and R² are both hydrogen or are both deuterium; -   R³ and R⁴ are both hydrogen or are both deuterium; -   R⁵ and R⁶ are both hydrogen or are both deuterium; -   R⁷ and R⁸ are both hydrogen or are both deuterium; -   R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; -   R¹¹ is hydrogen or deuterium; and -   R¹² and R¹³ are both deuterium.

The present invention also provides protonated versions of all of the compounds described in this specification that may be prepared by the method of the present invention. That is, for each compound described in this specification, the invention also includes the quaternary protonated amine form of the compound that may be prepared by the method of the present invention. These quaternary protonated amine form of the compounds may be present in the solid phase, for example in crystalline or amorphous form, and may be present in solution. These quaternary protonated amine form of the compounds may be associated with pharmaceutically acceptable anionic counter ions, including but not limited to those described in for example: “Handbook of Pharmaceutical Salts, Properties, Selection, and Use”, P. Heinrich Stahl and Camille G. Wermuth (Eds.), Published by VHCA (Switzerland) and Wiley-VCH (FRG), 2002.

Preparation of the Compounds of the Invention

The present invention provides synthetic methodology for the preparation of compounds of formula (I) and compounds of formula (II) as described herein. It is understood that in the following Reaction Schemes, combinations of substituents and/or variables of the depicted formulae are permissible only if such contributions result in stable compounds.

It will also be appreciated by those skilled in the art that in the processes described below the functional groups of intermediate compounds may need to be protected by suitable protecting groups. Such functional groups include hydroxy, amino, mercapto and carboxylic acid. Suitable protecting groups for hydroxy include trialkylsilyl or diarylalkylsilyl (for example, t-butyldimethylsilyl, t-butyldiphenylsilyl or trimethylsilyl), tetrahydropyranyl, benzyl, and the like. Suitable protecting groups for amino, amidino and guanidino include t-butoxycarbonyl, benzyloxycarbonyl, and the like. Suitable protecting groups for mercapto include —C(O)—R″ (where R″ is alkyl, aryl or arylalkyl), p-methoxybenzyl, trityl and the like. Suitable protecting groups for carboxylic acid include alkyl, aryl or arylalkyl esters.

Protecting groups may be added or removed in accordance with standard techniques, which are known to one of ordinary skill in the art and as described herein.

The use of protecting groups is described in detail in Green, T. W. and P. G. M. Wuts, Protective Groups in Organic Synthesis (1999), 3rd Ed., Wiley. As one of skill in the art would appreciate, the protecting group may also be a polymer resin such as a Wang resin, Rink resin or a 2-chlorotrityl-chloride resin.

It is understood that one of ordinary skill in the art would be able to make the compounds of the invention by methods similar to the methods described herein or by methods known to one of ordinary skill in the art. It is also understood that one of ordinary skill in the art would be able to make in a similar manner as described below other compounds of formula (I) and compound of formula (II) not specifically illustrated below by using the appropriate starting components and modifying the parameters of the synthesis as needed. In general, starting components may be obtained from sources such as Aldrich Chemical Co., Sigma, Lancaster Synthesis, Inc., Maybridge, Matrix Scientific, TCI, and Fluorochem USA, etc. or synthesized according to sources known to those skilled in the art (see, for example, Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 5th edition (Wiley, December 2000)) or prepared as described in this invention.

When using reagents containing deuterium, it may not always be possible to obtain reagents that are completely deuterated. Using reagents with the highest possible deuteration will result in maximum desired deuteration, including complete deuteration when using 100% deuterated reagents. Alternatively, it may be possible to use partially deuterated reagents such that less deuteration of the final product is achieved. It is understood to a person of skill in the art that partially deuterated compounds, mixtures of partially deuterated compounds with completely deuterated compounds and mixtures of non-deuterated compounds with partially deuterated compounds with completely deuterated compounds may be prepared by using non-fully deuterated reagents. The reaction schemes described herein are described with respect to using 100% deuterated reagents.

In the following Reaction Schemes, the following common abbreviations are used:

Ac for C₂-C₅acyl group

AcCl for C₂-C₅acyl chloride

Bn for benzyl

DBU for 1,8-diazabicyclo(5.4.0)undec-7-ene

DME for dimethyl ether

Et₂O for diethyl ether

MeOH for methanol

THF for tetrahydrofuran

The synthetic procedures described herein, especially when taken with the general knowledge in the art, provide sufficient guidance to those of ordinary skill in the art to perform the synthesis, isolation, and purification of the compounds of the present invention. Further, it is contemplated that the individual features of these embodiments and examples may be combined with the features of one or more other embodiments or examples.

Methods for resolution of diastereomeric mixtures or racemic mixtures of the compounds of formula (I) and compounds of formula (II) or intermediates prepared herein are well known in the art (e.g., E. L. Eliel and S. H. Wilen, in Stereochemistry of Organic Compounds; John Wiley & Sons: New York, 1994; Chapter 7, and references cited therein). Suitable processes such as crystallization (e.g. preferential crystallization, preferential crystallization in the presence of additives), asymmetric transformation of racemates, chemical separation (e.g. formation and separation of diastereomers such as diastereomeric salt mixtures or the use of other resolving agents; separation via complexes and inclusion compounds), kinetic resolution (e.g. with titanium tartrate catalyst), enzymatic resolution (e.g., lipase mediated) and chromatographic separation (e.g., HPLC with chiral stationary phase and/or with simulated moving bed technology, or supercritical fluid chromatography and related techniques) are some of the examples that may be applied (see e.g., T. J. Ward, Analytical Chemistry, 2002, 2863-2872).

For purposes of illustration only, an asterisk (*) in the formulae in the following Reaction Schemes indicates a carbon having two deuterium atoms attached thereto.

A. Preparation of Compounds of Formula (I)

In the following Reaction Scheme 1 compounds of formula (I) where R¹⁴, R¹⁵, and R¹⁶ are each hydrogen are illustrated as being prepared. It is understood that the specific stereoisomers of compounds of formula (I) can be prepared in a similar fashion utilizing the appropriately substituted chiral starting material. The present invention also encompasses the preparation of the pharmaceutically acceptable salts of the compounds of formula (I).

In general, compounds of formula (I), as set forth above in the Summary of the Invention, where R¹⁴, R¹⁵, and R¹⁶ are each hydrogen, can be prepared by the method disclosed in Reaction Scheme 1 wherein R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹ and R¹² are as described above in the Summary of the Invention for the compounds of formula (I), R is C₂-C₅acyl and Q is a leaving group, preferably trihaloacetimidate:

Compounds of formula (IA) and compounds of formula (IB) can be prepared by methods known to one skilled in the art or by methods disclosed herein or can be obtained commercially.

Compounds of formula (I) are prepared as illustrated above in Reaction Scheme 1 by first treating a compound of formula (IA) with a compound of formula (IB) under suitable etherification conditions such that upon reaction of the compound of formula (IA) with the compound of formula (IB), the stereochemical configuration of the carbon at the 1-position of the compound of formula (IA) is retained in the resulting compound of formula (IC). Preferably, such suitable conditions are catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate). The compound of formula (IC) is then reduced with a suitable deuterated or non-deuterated reducing agent to yield a compound of formula (I). Salts of the compound of formula (I) can be prepared by standard methods.

Compounds of formula (IA) can be prepared as illustrated below in Reaction Scheme 1A wherein PG is an oxygen-protecting group, preferably optionally substituted benzyl; R² is selected to form a compound of formula (IF) upon treatment with the compound of formula (ID), followed by cyclization, and is selected, but is not limited to, from the following radicals wherein the

line in the following represents the

bond between R² and the OR group in compounds of formula (IE):

where each Y is halo; R is H, C₂-C₅acyl or an oxygen-protecting group; and R¹¹, R¹² and R¹³ are as defined above in the Summary of the Invention:

In general, the compounds of formula (IA) are prepared in Reaction Scheme 1A by first treating a compound of formula (ID) with a compound of formula (IE) in an aprotic solvent, such as toluene, dichloromethane, or ethyl acetate, followed by the treatment with an cyclizing agent, such as a C₂-C₅acyl halide or C₂-C₅acyl anhydride, at temperatures of between about 0° C. to reflux temperature, preferably at reflux temperature, to form a compound of formula (IF). Alternatively, a compound of formula (ID) is first treated with a compound of formula (IE) in an aprotic solvent to yield a corresponding intermediate, which is then treated with a cyclizing agent to form compounds of formula (IF). Compounds of formula (IF) are then subjected to standard deprotection conditions known to one skilled in the art, such as hydrogenation in the presence of a catalyst under appropriate conditions, to form the compound of formula (IA), which is isolated from the reaction mixture by standard isolation techniques.

The following Reaction Schemes 2-16 illustrate various aspects of the methods of preparing compounds of formula (I) having the following trans stereochemistry at positions 1 and 2 of the cyclohexyl ring:

It is understood, however, that compounds of formula (I) having the following stereochemistry at positions 1 and 2 of the cyclohexyl ring:

can be prepared in a similar manner using the appropriate chiral starting material or chiral reagent.

In addition, the following Reaction Schemes 2-16 illustrate various aspects of the methods of preparing compounds of formula (I) having the following stereochemistry at position 3 of the pyrrolidinyl ring:

It is understood, however, that compounds of formula (I) having the following stereochemistry at position 3 of the pyrrolidinyl ring:

can be prepared in a similar manner using the appropriate chiral starting material or chiral reagent.

In the following Reaction Scheme 2, the compound of formula (I-1) is prepared. The compound of formula (I-1) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each deuterium; R⁵, R⁶, R⁷ and R⁸ are each hydrogen; R⁹ and R¹⁰ are each methoxy; and R¹¹, R¹² and R¹³ are each hydrogen, and R¹⁴, R¹⁵, and R¹⁶ are each hydrogen:

The compound of formula (IG) is commercially available, for example, from Aldrich Chemical Co., or can be prepared by methods known to one skilled in the art. Deuterated borane and lithium aluminum deuteride are commercially available, for example, from Cambridge Isotope Laboratories. Compounds of formula (IA-1) can be prepared by the methods disclosed herein.

In general for the preparation of the compounds of formula (I-1), the compound of formula (IG) is treated with trichloroacetonitrile in the presence of a catalyst, preferably DBU, to form the compound of formula (IB-1). Etherification of compound of formula (IB-1) with compound of formula (IA-1) under catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate in an aprotic solvent, such as toluene) gives the corresponding imido-ether of formula (IC-1). Successive reduction of compound of formula (IC-1) with a suitable deuterated reducing agent, for example, deuterated borane, NaBD₄/Lewis acid, KBD₄, or lithium aluminum deuteride, provides the compound of formula (I-1). Subsequent treatment with hydrogen chloride in methanol under standard conditions gives the hydrochloride salt of the compound of formula (I-1).

In the following Reaction Scheme 3, the compound of formula (I-2) is prepared. The compound of formula (I-2) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each deuterium; R⁵ and R⁶ are each hydrogen, R⁷ and R⁸ are each deuterium; R⁹ and R¹⁰ are each methoxy; and R¹¹, R¹² and R¹³ are each hydrogen, and R¹⁴, R¹⁵, and R¹⁶ are each hydrogen:

The compound of formula (IH) is commercially available, for example, from CDN Isotopes. Deuterated borane and lithium aluminum deuteride are commercially available, for example, from Cambridge Isotope Laboratories. Compounds of formula (IA-1) can be prepared by the methods disclosed herein.

In general for the preparation of the compound of formula (I-2), the compound of formula (IH) is treated with a suitable reducing agent, for example, lithium aluminum hydride or borane, under standard reducing conditions to form the compound of formula (IJ). The compound of formula (IJ) is treated with trichloroacetonitrile in the presence of a catalyst, preferably DBU, in an aprotic solvent, preferably dichloromethane, to form the compound of formula (IB-2). Etherification of compound of formula (IB-2) with compound of formula (IA-1) under catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate in an aprotic solvent, such as toluene) gives the corresponding imido-ether of formula (IC-2). Successive reduction of compound of formula (IC-2) with a suitable deuterated reducing agent, for example, deuterated borane, NaBD₄/Lewis acid, KBD₄ or lithium aluminum deuteride, provides the compound of formula (I-2). Subsequent treatment with hydrogen chloride in methanol under standard conditions gives the hydrochloride salt of the compound of formula (I-2).

In the following Reaction Scheme 4, the compound of formula (I-3) and the compound of formula (I-4) are prepared. The compound of formula (I-3) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each deuterium; R⁵, R⁶, R⁷ and R⁸ are each deuterium; R⁹ and R¹⁰ are each methoxy; and R¹¹, R¹² and R¹³ are each hydrogen. The compound of formula (I-4) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each hydrogen; R⁵, R⁶, R⁷ and R⁸ are each deuterium; R⁹ and R¹⁰ are each methoxy; and R¹¹, R¹² and R¹³ are each hydrogen, and R¹⁴, R¹⁵, and R¹⁶ are each hydrogen:

The compound of formula (IH) is commercially available, for example, from CDN Isotopes. Deuterated borane and lithium aluminum deuteride are commercially available, for example, from Cambridge Isotope Laboratories. Compounds of formula (IA-1) can be prepared by the methods disclosed herein.

In general for the preparation of the compound of formula (I-3) and the compound of formula (I-4), the compound of formula (IH) is treated with a suitable reducing agent, for example, lithium aluminum deuteride, under standard reducing conditions to form the compound of formula (IK). The compound of formula (IK) is treated with trichloroacetonitrile in the presence of a catalyst, preferably DBU, in an aprotic solvent, preferably dichloromethane, to form the compound of formula (IB-3). Etherification of compound of formula (IB-3) with compound of formula (IA-1) under catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate in an aprotic solvent, such as toluene) gives the corresponding imido-ether of formula (IC-3). Successive reduction of compound of formula (IC-3) with a suitable deuterated reducing agent, for example, deuterated borane, NaBD₄/Lewis acid, KBD₄, or lithium aluminum deuteride, provides the compound of formula (I-3). Subsequent treatment with hydrogen chloride in methanol under standard conditions gives the hydrochloride salt of the compound of formula (I-3). Alternatively, successive reduction of compound of formula (IC-3) with a suitable reducing agent, for example, borane, NaBH₄/Lewis acid, KBH₄, or lithium aluminum hydride, provides the compound of formula (I-4). Subsequent treatment with hydrogen chloride in methanol under standard conditions gives the hydrochloride salt of the compound of formula (I-4).

In the following Reaction Scheme 5, the compound of formula (I-5) is prepared. The compound of formula (I-5) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each deuterium; R⁵, R⁶, R⁷ and R⁸ are each hydrogen; R⁹ is methoxy; R¹⁰ is —OCD₃; and R¹¹, R¹² and R¹³ are each hydrogen, and R¹⁴, R¹⁵, and R¹⁶ are each hydrogen:

The compound of formula (IL) is commercially available, for example, from Aldrich Chemical Co., or can be prepared by methods known to one skilled in the art. CD₃I is commercially available. Deuterated borane and lithium aluminum deuteride are commercially available, for example, from Cambridge Isotope Laboratories. Compounds of formula (IA-1) can be prepared by the methods disclosed herein.

In general for the preparation of the compound of formula (I-5), the compound of formula (IL) is treated with CD₃I under standard aromatic nucleophilic substitution conditions to form a compound of formula (IM). The compound of formula (IM) is then treated with trichloroacetonitrile in the presence of a catalyst, preferably DBU, in an aprotic solvent, preferably dichloromethane, to form the compound of formula (IB-4). Etherification of compound of formula (IB-4) with compound of formula (A-1) under catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate in an aprotic solvent, such as toluene) gives the corresponding imido-ether of formula (IC-4). Successive reduction of compound of formula (IC-4) with a suitable deuterated reducing agent, for example, deuterated borane, NaBD₄/Lewis acid, KBD₄, or lithium aluminum deuteride, provides the compound of formula (I-5). Subsequent treatment with hydrogen chloride in methanol under standard conditions gives the hydrochloride salt of the compound of formula (I-5).

In the following Reaction Scheme 6, the compound of formula (I-5) and the compound of (I-6) are prepared. As noted above, the compound of formula (I-5) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each deuterium; R⁵, R⁶, R⁷ and R⁸ are each hydrogen; R⁹ is methoxy; R¹⁰ is —OCD₃; and R¹¹, R¹² and R¹³ are each hydrogen. The compound of formula (I-6) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each deuterium; R⁵ and R⁶ are each deuterium; R⁷ and R⁸ are each hydrogen; R⁹ is methoxy; R¹⁰ is —OCD₃; and R¹¹, R¹² and R¹³ are each hydrogen, and R¹⁴, R¹⁵, and R¹⁶ are each hydrogen:

The compound of formula (IN) is commercially available, for example, from Aldrich Chemical Co., or can be prepared by methods known to one skilled in the art. CD₃I is commercially available. Deuterated borane and lithium aluminum deuteride are commercially available, for example, from Cambridge Isotope Laboratories. Compounds of formula (IA-1) can be prepared by the methods disclosed herein.

In general for the preparation of the compound of formula (I-6), the compound of formula (IN) is treated with CD₃I under standard aromatic nucleophilic substitution conditions to form a compound of formula (IO). The compound of formula (IO) is then treated with a deuterated reducing agent, such as lithium aluminum deuteride, under standard reducing conditions and then treated with trichloroacetonitrile in the presence of a catalyst, preferably DBU, to form the compound of formula (IB-5). Etherification of compound of formula (IB-5) with compound of formula (IA-1) under catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate in an aprotic solvent, such as toluene) gives the corresponding imido-ether of formula (IC-5). Successive reduction of compound of formula (IC-5) with a suitable deuterated reducing agent, for example, deuterated borane, NaBD₄/Lewis acid, KBD₄, or lithium aluminum deuteride, provides the compound of formula (I-6). Subsequent treatment with hydrogen chloride in methanol under standard conditions gives the hydrochloride salt of the compound of formula (I-6).

In general for the preparation of the compound of formula (I-5), the compound of formula (IN) is treated with CD₃I under standard aromatic nucleophilic substitution conditions to form a compound of formula (IO). The compound of formula (IO) is then treated with a reducing agent, such as lithium aluminum hydride or borane, under standard reducing conditions to form a compound of formula (IP). The compound of formula (IP) is then treated with trichloroacetonitrile in the presence of a catalyst, preferably DBU, in an aprotic solvent, preferably dichloromethane, to form the compound of formula (IB-6). Etherification of compound of formula (IB-6) with compound of formula (IA-1) under catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate in an aprotic solvent, such as toluene) gives the corresponding imido-ether of formula (IC-6). Successive reduction of compound of formula (IC-6) with a suitable deuterated reducing agent, for example, deuterated borane, NaBD₄/Lewis acid, KBD₄, or lithium aluminum deuteride, provides the compound of formula (I-5). Subsequent treatment with hydrogen chloride in methanol under standard conditions gives the hydrochloride salt of the compound of formula (I-5).

In the following Reaction Scheme 7, the compound of formula (I-7) and the compound of (I-8) are prepared. The compound of formula (I-7) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each deuterium; R⁵ and R⁶ are each deuterium; R⁷ and R⁸ are each hydrogen; R⁹ is —OCD₃; R¹⁰ is methoxy; and R¹¹, R¹² and R¹³ are each hydrogen. The compound of formula (I-8) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each deuterium; R⁵, R⁶, R⁷ and R⁸ are each hydrogen; R⁹ is —OCD₃; R¹⁰ is methoxy; and R¹¹, R¹² and R¹³ are each hydrogen, and R¹⁴, R¹⁵, and R¹⁶ are each hydrogen:

The compound of formula (IQ) is commercially available, for example, from Aldrich Chemical Co., or can be prepared by methods known to one skilled in the art. Deuterated borane, lithium aluminum deuteride and CD₃I are also commercially available, for example, from Cambridge Isotope Laboratories. Compound of formula (IA-1) can be prepared by the methods disclosed herein.

In general for the preparation of the compound of formula (I-7) or the compound of formula (I-8), the compound of formula (IQ) is treated with CD₃I under standard aromatic nucleophilic substitution conditions to form a compound of formula (IR). The compound of formula (IR) is then treated with a deuterated reducing agent, such as lithium aluminum deuteride, followed by treatment with trichloroacetonitrile in the presence of a catalyst, preferably DBU, in an aprotic solvent, preferably dichloromethane, to form the compound of formula (IB-7). Etherification of compound of formula (IB-7) with compound of formula (IA-1) under catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate in an aprotic solvent, such as toluene) gives the corresponding imido-ether of formula (IC-7). The compound of formula (IC-7) is then treated with a deuterated reducing agent, such as lithium aluminum deuteride or deuterated borane, in an aprotic solvent, such as THF, followed by workup with methanolic hydrochloride, for example, to produce the hydrochloride salt of the compound of formula (I-7).

Alternatively, the compound of formula (I-8) is prepared, as set forth above in Reaction Scheme 7, by reducing a compound of formula (IR) with a reducing agent such as lithium aluminum hydride to produce compound of formula (IS). Treatment of compound of formula (IS) with trichloroacetonitrile in the presence of a catalyst, preferably DBU, in an aprotic solvent, preferably dichloromethane, forms the compound of formula (IB-8). Etherification of compound of formula (IB-8) with compound of formula (IA-1) under catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate in an aprotic solvent, such as toluene) gives the corresponding imido-ether of formula (IC-8). The compound of formula (IC-8) is then treated with a deuterated reducing agent, such as lithium aluminum deuteride or deuterated borane in an aprotic solvent such as THF followed by workup with methanolic hydrochloride, for example, to produce the hydrochloride salt of the compound of formula (I-8).

In the following Reaction Scheme 8, the compound of formula (I-9), the compound of formula (I-10), the compound of formula (I-11) and the compound of (I-12) are prepared. The compound of formula (I-9) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each hydrogen; R⁵ and R⁶ are each deuterium; R⁷ and R⁸ are each hydrogen; R⁹ and R¹⁰ are both —OCD₃; and R¹¹, R¹² and R¹³ are each hydrogen. The compound of formula (I-10) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each hydrogen; R⁵ and R⁶ are each hydrogen; R⁷ and R⁸ are each hydrogen; R⁹ and R¹⁰ are both —OCD₃; and R¹¹, R¹² and R¹³ are each hydrogen. The compound of formula (I-11) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each deuterium; R⁵ and R⁶ are each deuterium; R⁷ and R⁸ are each hydrogen; R⁹ and R¹⁰ are both —OCD₃; and R¹¹, R¹² and R¹³ are each hydrogen. The compound of formula (I-12) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each deuterium; R⁵ and R⁶ are each hydrogen; R⁷ and R⁸ are each hydrogen; R⁹ and R¹⁰ are both —OCD₃; and R¹¹, R¹² and R¹³ are each hydrogen, and R¹⁴, R¹⁵, and R¹⁶ are each hydrogen:

The compound of formula (IT) is commercially available, for example, from Aldrich Chemical Co., or can be prepared by methods known to one skilled in the art. Deuterated borane, lithium aluminum deuteride and CD₃I are also commercially available, for example, from Cambridge Isotope Laboratories. Compound of formula (IA-1) can be prepared by the methods disclosed herein.

In general for the preparation of the compound of formula (I-9) or the compound of formula (I-11), the compound of formula (IT) is treated with CD₃I under standard aromatic nucleophilic substitution conditions to form a compound of formula (IU). The compound of formula (IU) is then treated with a deuterated reducing agent such as lithium aluminum deuteride followed by treatment with trichloroacetonitrile in the presence of a catalyst, preferably DBU, in an aprotic solvent, preferably dichloromethane, to form the compound of formula (IB-9). Etherification of compound of formula (IB-9) with compound of formula (IA-1) under catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate in an aprotic solvent, such as toluene) gives the corresponding imido-ether of formula (IC-9). The compound of formula (IC-9) is then treated with a reducing agent, such as borane, in an aprotic solvent, such as THF, followed by workup with methanolic hydrochloride, for example, to produce the hydrochloride salt of the compound of formula (I-9).

Alternatively, the compound of formula (IC-9) is treated with a deuterated reducing agent, such as deuterated borane, in an aprotic solvent, such as THF, followed by workup with methanolic hydrochloride, for example, to produce the hydrochloride salt of the compound of formula (I-11).

In general for the preparation of the compound of formula (I-10) or the compound of formula (I-12), a compound of formula (IU) can be reduced with a reducing agent, such as lithium aluminum hydride or borane, to produce compound of formula (IV). Treatment of compound of formula (IV) with trichloroacetonitrile in the presence of a catalyst, preferably DBU, in an aprotic solvent, preferably dichloromethane, forms the compound of formula (IB-10). Etherification of compound of formula (IB-10) with compound of formula (IA-1) under catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate in an aprotic solvent, such as toluene) gives the corresponding imido-ether of formula (IC-10). The compound of formula (IC-10) is then treated with a reducing agent, such as borane, in an aprotic solvent, such as THF, followed by workup with methanolic hydrochloride, for example, to produce the hydrochloride salt of the compound of formula (I-10).

Alternatively, compound of formula (IC-10) is treated with a deuterated reducing agent, such as deuterated borane, in an aprotic solvent, such as THF, followed by workup with methanolic hydrochloride, for example, to produce the hydrochloride salt of the compound of formula (I-12).

Alternatively, in the following Reaction Scheme 9, the compound of formula (I-10) and the compound of formula (I-12) are prepared. The compound of formula (I-10), as noted above, is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each hydrogen; R⁵ and R⁶ are each hydrogen; R⁷ and R⁸ are each hydrogen; R⁹ and R¹⁰ are both —OCD₃; and R¹¹, R¹² and R¹³ are each hydrogen. The compound of formula (I-12) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each deuterium; R⁵ and R⁶ are each hydrogen; R⁷ and R⁸ are each hydrogen; R⁹ and R¹⁰ are both —OCD₃; and R¹¹, R¹² and R¹³ are each hydrogen, and R¹⁴, R¹⁵, and R¹⁶ are each hydrogen:

The compound of formula (IW) is commercially available, for example, from Aldrich Chemical Co., or can be prepared by methods known to one skilled in the art. Deuterated borane and CD₃I are also commercially available, for example, from Cambridge Isotope Laboratories. Compound of formula (IA-1) can be prepared by methods disclosed herein.

In general for the preparation of the compounds of formula (I-10) and the compound of formula (I-12), the compound of formula (IW) is treated with CD₃I under standard aromatic nucleophilic substitution conditions to form a compound of formula (IV). The compound of formula (IV) is then treated with trichoroacetonitrile in the presence of a catalyst, preferably DBU, in an aprotic solvent, preferably dichloromethane, to form the compound of formula (IB-10). Etherification of compound of formula (IB-10) with a compound of formula (IA-1) under catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate in an aprotic solvent, such as toluene) gives the corresponding imido-ether of formula (IC-10). The compound of formula (IC-10) is then treated with a reducing agent, such as borane, in an aprotic solvent, such as THF, followed by a workup with methanolic hydrochloride, for example, to produce the hydrochloride salt of the compound of formula (I-10).

Alternatively, the compound of formula (IC-10) is treated with a deuterated reducing agent, such as deuterated borane, in an aprotic solvent, such as THF, followed by workup with methanolic hydrochloride, for example, to produce the hydrochloride salt of the compound of formula (I-12).

In the following Reaction Scheme 10, the compound of formula (I-13) and the compound of (I-14) are prepared. The compound of formula (I-13) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each hydrogen; R⁵ and R⁶ are each hydrogen; R⁷ and R⁸ are each deuterium; R⁹ is methoxy, R¹⁰ is —OCD₃; and R¹¹, R¹² and R¹³ are each hydrogen. The compound of formula (I-12) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each deuterium; R⁵ and R⁶ are each hydrogen; R⁷ and R⁸ are each deuterium; R⁹ is methoxy, R¹⁰ is —OCD₃; and R¹¹, R¹² and R¹³ are each hydrogen, and R¹⁴, R¹⁵, and R¹⁶ are each hydrogen:

The compound of formula (IX) is commercially available, for example, from CDN Isotopes, or can be prepared by methods known to one skilled in the art. Deuterated borane and CD₃I are also commercially available, for example, from Cambridge Isotope Laboratories. Compound of formula (IA-1) can be prepared by the methods disclosed herein.

In general for the preparation of the compound of formula (I-13) or the compound of formula (I-14), the compound of formula (IX) is treated with CD₃I under standard aromatic nucleophilic substitution conditions to form a compound of formula (IX-2). The compound of formula (IX-2) is treated with a reducing agent such as lithium aluminum hydride, under standard reducing conditions to form a compound of formula (IY). The compound of formula (IY) is then treated trichloroacetonitrile in the presence of a catalyst, preferably DBU, in an aprotic solvent, preferably dichloromethane, to form the compound of formula (IB-11). Etherification of compound of formula (IB-11) with compound of formula (IA-1) under catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate in an aprotic solvent, such as toluene) gives the corresponding imido-ether of formula (IC-11). The compound of formula (IC-11) is then treated with a reducing agent, such as borane, in an aprotic solvent, such as THF, followed by workup with methanolic hydrochloride, for example, to produce the hydrochloride salt of the compound of formula (I-13).

Alternatively, compound of formula (IC-11) is treated with a deuterated reducing agent, such as deuterated borane, in an aprotic solvent, such as THF, followed by workup with methanolic hydrochloride, for example, to produce the hydrochloride salt of the compound of formula (I-14).

In the following Reaction Scheme 11, the compound of formula (I-15) and the compound of (I-16) are prepared. The compound of formula (I-15) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each hydrogen; R⁵, R⁶, R⁷ and R⁸ are each deuterium; R⁹ and R¹⁰ are both methoxy; and R¹¹, R¹² and R¹³ are each deuterium. The compound of formula (I-16) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each deuterium; R⁵, R⁶, R⁷ and R⁸ are each deuterium; R⁹ and R¹⁰ are both methoxy; and R¹¹, R¹² and R¹³ are each deuterium, and R¹⁴, R¹⁵, and R¹⁶ are each hydrogen:

The compound of formula (IZ) is commercially available, for example, from CDN Isotope, or can be prepared by methods known to one skilled in the art. The compound of formula (IB-3) can be prepared according to methods disclosed herein. Deuterated borane is also commercially available, for example, from Cambridge Isotope Laboratories.

In general, the compound of formula (IZ) is treated with a C₂-C₅acyl chloride according to the procedures described in Henrot, S. et al., Synthetic Communications (1986), Vol. 16, No. 2, pp. 183-190 to form a compound of formula (IAA). The compound of formula (IAA) is condensed with trans-2-(benzyloxy)cyclohexanamine in a suitable solvent, preferably dichloromethane, to form a compound of formula (IBB). The compound of formula (IBB) is subjected to standard hydrogenolysis condition (Pd/C, H₂ in a suitable solvent, such as toluene, methanol, ethyl acetate, Ra—Ni—H₂, Pt/C—H₂) at ambient temperature to remove the benzyl group to give compound of formula (IA-2). Etherification of compound of formula (IA-2) with compound of formula (IB-3) under catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate) gives the corresponding compound of formula (IC-12). Successive reduction of compound of formula (IC-12) with a suitable deuterated reducing agent, for example, deuterated borane, NaBD₄/Lewis acid, KBD₄, or lithium aluminum deuteride, provides the compound of formula (I-16). Subsequent treatment with hydrogen chloride in methanol under standard conditions gives the hydrochloride salt of the compound of formula (I-16).

Alternatively, successive reduction of compound of formula (IC-12) with a suitable reducing agent, for example, borane, NaBH₄/Lewis acid, KBH₄, or lithium aluminum hydride, provides the compound of formula (I-15). Subsequent treatment with hydrogen chloride in methanol under standard conditions gives the hydrochloride salt of the compound of formula (I-15).

In the following Reaction Scheme 12, the compound of formula (I-17) is prepared. The compound of formula (I-17) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each deuterium; R⁵, R⁶, R⁷ and R⁸ are each hydrogen; R⁹ is methoxy and R¹⁰ is hydroxy; and R¹¹, R¹² and R¹³ are each hydrogen, and R¹⁴, R¹⁵, and R¹⁶ are each hydrogen:

The compound of formula (IL) and benzyl bromide are commercially available, for example, from Aldrich Chemical Co., or can be prepared by methods known to one skilled in the art. Deuterated borane and lithium aluminum deuteride are commercially available, for example, from Cambridge Isotope Laboratories. The compound of formula (IA-1) can be prepared by methods disclosed herein.

In general for the preparation of the compound of formula (I-17), the compound of formula (IL) is treated with benzyl bromide under standard aromatic nucleophilic substitution conditions to form the compound of formula (ICC). The compound of formula (ICC) is then treated with trichloracetonitrile in the presence of a catalyst, preferably DBU, in an aprotic solvent to form the compound of formula (IB-12). Etherification of the compounds of formula (IB-12) with the compound of formula (IA-1) under catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate in an aprotic solvent, such as toluene) gives the corresponding imido-ether compound of formula (IC-12). Reduction of the compound of formula (IC-12) with a suitable deuterated reducing agent, for example, deuterated borane, NaBD₄/Lewis acid, KBD₄ or lithium aluminum deuteride, in an aprotic solvent, such as tetrahydrofuran, followed by workup with methanolic hydrochloride and hydrogenation over Pd—C in methanol provides the hydrochloride salt of the compound of formula (I-17).

In the following Reaction Scheme 13, the compound of formula (I-18) is prepared. The compound of formula (I-18) is a compound of formula (II) wherein R¹, R², R³ and R⁴ are each deuterium; R⁵ and R⁶ are each deuterium; R⁷ and R⁸ are each hydrogen; R⁹ is methoxy and R¹⁰ is hydroxy; and R¹¹, R¹² and R¹³ are each hydrogen, and R¹⁴, R¹⁵, and R¹⁶ are each hydrogen:

The compound of formula (IN) and benzyl bromide is commercially available, for example, from Aldrich Chemical Co, or can be prepared by methods known to one skilled in the art. Deuterated borane and lithium aluminum deuteride are commercially available, for example, from Cambridge Isotope Laboratories. The compound of formula (IA-1) can be prepared by methods disclosed herein.

In general for the preparation of the compound of formula (I-18), the compound of formula (IN) is reduced with a reducing agent, such as lithium aluminum deuteride or deuterated borate, under standard reducing conditions, for example, in the presence of an aprotic solvent, such as tetrahydrofuran, to yield a compound of formula (IDD). The compound of formula (IDD) is then treated with benzyl bromide under standard aromatic nucleophilic substitution conditions to produce the compound of formula (IEE). The compound of formula (IEE) is then treated with trichloracetonitrile in the presence of a catalyst, preferably DBU, in an aprotic solvent to form the compound of formula (IB-13). Etherification of the compounds of formula (B-13) with the compound of formula (IA-1) under catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate in an aprotic solvent, such as toluene) gives the corresponding imido-ether compound of formula (IC-13). Reduction of the compound of formula (IC-13) with a suitable deuterated reducing agent, for example, deuterated borane, NaBD₄/Lewis acid, KBD₄ or lithium aluminum deuteride, in an aprotic solvent, such as tetrahydrofuran, followed by workup with methanolic hydrochloride and hydrogenation over Pd—C in methanol provides the hydrochloride salt of the compound of formula (I-18).

In the following Reaction Scheme 14, the compound of formula (I-19) and the compound of formula (I-20) are prepared. The compound of formula (I-19) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each hydrogen; R⁵, R⁶, R⁷ and R⁸ are each deuterium; R⁹ is methoxy and R¹⁰ is hydroxy; and R¹¹, R¹² and R¹³ are each hydrogen. The compound of formula (I-20) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each deuterium; R⁵, R⁶, R⁷ and R⁸ are each deuterium; R⁹ is methoxy and R¹⁰ is hydroxy; and R¹¹, R¹² and R¹³ are each hydrogen, and R¹⁴, R¹⁵, and R¹⁶ are each hydrogen:

The compound of formula (IX) is commercially available, for example, from CDN Isotope, or can be prepared by methods known to one skilled in the art. Benzyl bromide is commercially available, for example, from Aldrich Chemical Co., or can be prepared according to methods known to one skilled in the art. Deuterated borane and lithium aluminum deuteride are commercially available, for example, from Cambridge Isotope Laboratories. The compound of formula (IA-1) can be prepared by methods disclosed herein.

In general for the preparation of the compound of formula (I-19), the compound of formula (IX) is reduced with a reducing agent, such as lithium aluminum deuteride, in the presence of an aprotic solvent to yield a compound of formula (IFF). The compound of formula (IFF) is then treated with benzyl bromide under standard aromatic nucleophilic substitution conditions to produce the compound of formula (IGG). The compound of formula (IGG) is then treated with trichloracetonitrile in the presence of a catalyst, preferably DBU, in an aprotic solvent to form the compound of formula (B-14). Etherification of the compounds of formula (IB-14) with the compound of formula (IA-1) under catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate in an aprotic solvent, such as toluene) gives the corresponding imido-ether compound of formula (IC-14). Reduction of the compound of formula (IC-14) with a suitable deuterated reducing agent, for example, deuterated borane, in an aprotic solvent, such as tetrahydrofuran, followed by workup with methanolic hydrochloride and hydrogenation over Pd—C in methanol provides the hydrochloride salt of the compound of formula (I-20).

Alternatively, the compound of formula (IC-14) is reduced with a suitable reducing agent, for example, borane, in an aprotic solvent, such as tetrahydrofuran, followed by workup with methanolic hydrochloride and hydrogenation over Pd—C in methanol to provide the hydrochloride salt of the compound of formula (I-19).

Alternatively, in the following Reaction Scheme 15, the compound of formula (I-19) and the compound of formula (I-20), as defined above in Reaction Scheme 14, are prepared:

The compound of formula (IHH) is commercially available, for example, from Aldrich Chemical Co., or can be prepared by methods known to one skilled in the art. Benzyl bromide is commercially available, for example, from Aldrich Chemical Co., or can be prepared according to methods known to one skilled in the art. Deuterated borane and lithium aluminum deuteride are commercially available, for example, from Cambridge Isotope Laboratories. The compound of formula (IA-1) can be prepared by methods disclosed herein.

In general for the preparation of the compound of formula (I-19), the compound of formula (IHH) is reduced with a deuterated reducing agent, such as lithium aluminum deuteride, in the presence of an aprotic solvent to yield a compound of formula (IJJ). The compound of formula (IJJ) is then treated with benzyl bromide under standard aromatic nucleophilic substitution conditions to produce the compound of formula (IK). The compound of formula (IKK) is then reacted with mesylate chloride under standard mesylation conditions to form the mesylate intermediate, which is then treated with potassium cyanide under standard nucleophilic substitution conditions to form the compound of formula (ILL). The compound of formula (ILL) is then hydrolyzed under standard hydrolysis conditions, such as treatment with potassium hydroxide, to form the compound of formula (IMM). The compound of formula (IMM) is then reduced with a deuterated reducing agent, such as lithium aluminum deuteride, in the presence of an aprotic solvent to yield a compound of formula (IGG). The compound of formula (IGG) is then treated with trichloracetonitrile in the presence of a catalyst, preferably DBU, in an aprotic solvent to form the compound of formula (IB-14). Etherification of the compounds of formula (IB-14) with the compound of formula (A-1) under catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate in an aprotic solvent, such as toluene) gives the corresponding imido-ether compound of formula (C-14). Reduction of the compound of formula (IC-14) with a suitable deuterated reducing agent, for example, deuterated borane, in an aprotic solvent, such as tetrahydrofuran, followed by workup with methanolic hydrochloride and hydrogenation over Pd—C in methanol provides the hydrochloride salt of the compound of formula (I-20). Alternatively, the compound of formula (IC-14) is reduced with a suitable reducing agent, for example, borane, in an aprotic solvent, such as tetrahydrofuran, followed by workup with methanolic hydrochloride and hydrogenation over Pd—C in methanol to provide the hydrochloride salt of the compound of formula (I-19).

In the following Reaction Scheme 16, the compound of formula (I-21) is prepared. The compound of formula (I-21) is a compound of formula (I) wherein R¹, R², R³ and R⁴ are each deuterium; R⁵ and R⁶ are each deuterium, R⁷ and R⁸ are each hydrogen; R⁹ is hydroxy and R¹⁰ is methoxy; and R¹¹, R¹² and R¹³ are each hydrogen, and R¹⁴, R¹⁵, and R¹⁶ are each hydrogen:

The compound of formula (IQ) is commercially available, for example, from Aldrich Chemical Co, or can be prepared by methods known to one skilled in the art. Benzyl bromide is commercially available, for example, from Aldrich Chemical Co., or can be prepared according to methods known to one skilled in the art. Deuterated borane and lithium aluminum deuteride are commercially available, for example, from Cambridge Isotope Laboratories. The compound of formula (IA-1) can be prepared by methods disclosed herein.

In general for the preparation of the compound of formula (I-21), the compound of formula (IQ) is reduced with a reducing agent, such as lithium aluminum deuteride or deuterated borane, in the presence of an aprotic solvent, such as tetrahydrofuran, to yield a compound of formula (IOO). The compound of formula (IOO) is then treated with benzyl bromide under standard aromatic nucleophilic substitution conditions to produce the compound of formula (IPP). The compound of formula (IPP) is then treated with trichloracetonitrile in the presence of a catalyst, preferably DBU, in an aprotic solvent to form the compound of formula (IB-15). Etherification of the compounds of formula (IB-15) with the compound of formula (IA-1) under catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate in an aprotic solvent, such as toluene) gives the corresponding imido-ether compound of formula (IC-15). Reduction of the compound of formula (IC-15) with a suitable deuterated reducing agent, for example, deuterated borane or lithium aluminum deuteride, in an aprotic solvent, such as tetrahydrofuran, followed by workup with methanolic hydrochloride and hydrogenation over Pd—C in methanol provides the hydrochloride salt of the compound of formula (I-21).

In the following Reaction Scheme 16a, the compound of formula (I-22) is prepared. The compound of formula (I-22) is a compound of formula (I) wherein R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R¹¹, R¹² and R¹³ are all hydrogen; R⁹ and R¹⁰ are both methoxy; and R¹⁴, R¹⁵ and R¹⁶ are each deuterium:

The compound of formula (1a) is a compound of formula (1), as defined herein, and is prepared according to the methods disclosed in PCT Published Patent Application, WO 2004/099137.

In general, Compound (1-22) was synthesized according to Reaction Scheme 16a using the procedure of Tuck et al. (K. L. Tuck, Tan, H-W, Hayball, P. J.; J. Labelled Cpd. Radiopharma. 2000, 43, 817-823), as described in more detail below in Example 5A below.

It is understood that any of the compounds of formula (I) prepared above in Reaction Schemes 1-16 can be used as the starting material in the above Reaction Scheme 16a to produce the corresponding compounds of formula (I-22) wherein the phenyl ring is deuterated.

In addition to the above Reaction Schemes, compounds of formula (I) wherein R¹ and R² are both hydrogen and R³ and R⁴ are both deuterium or compounds of formula (I) wherein R¹ and R² are both deuterium and R³ and R⁴ are both hydrogen can be prepared by treating the appropriate compound of formula (C) with a reducing agent under mild conditions to form the following intermediate compounds:

where R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², and R¹³ are as defined above for compounds of formula (I), which can then be treated with a deuterated reducing agent under mild conditions to prepare compounds of formula (I) wherein R¹ and R² are both hydrogen and R³ and R⁴ are both deuterium or compounds of formula (I) wherein R¹ and R² are both deuterium and R³ and R⁴ are both hydrogen. Alternatively, the appropriate compound of formula (C) can be first treated with a deuterated reducing agent under mild conditions to form the following intermediate compounds:

where R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹² and R¹³ are as defined above for compounds of formula (I), which can then be treated with a reducing agent under mild conditions to prepare compounds of formula (I) wherein R¹ and R² are both hydrogen and R³ and R⁴ are both deuterium or compounds of formula (I) wherein R¹ and R² are both deuterium and R³ and R⁴ are both hydrogen. B. Preparation of Compounds of Formula (II)

In the following Reaction Scheme 17 compounds of formula (II) are illustrated as being prepared. It is understood that the specific stereoisomers of compounds of formula (II) can be prepared in a similar fashion utilizing the appropriately substituted chiral starting material. The present invention also encompasses the preparation of the pharmaceutically acceptable salts of the compounds of formula (II).

In general, compounds of formula (II), as set forth above in the Summary of the Invention, can be prepared by the method disclosed in Reaction Scheme 17 wherein R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹ and R¹² are as described above in the Summary of the Invention for compounds of formula (II), R is C₂-C₅acyl and Q is a leaving group, preferably trihaloacetimidate:

Compounds of formula (IIA) and compounds of formula (IIB) can be prepared by methods known to one skilled in the art or by methods disclosed herein or can be obtained commercially.

Compounds of formula (II) are prepared as illustrated above in Reaction Scheme 17 by first treating a compound of formula (IIA) with a compound of formula (IIB) under suitable etherification conditions such that upon reaction of the compound of formula (IIA) with the compound of formula (IIB), the stereochemical configuration of the carbon at the 1-position of the compound of formula (IIA) is retained in the resulting compound of formula (IIC). Preferably, such suitable conditions are catalytic Lewis acid conditions (e.g., HBF₄ etherate or BF₃ etherate). The compound of formula (IIC) is then reduced with a suitable deuterated or non-deuterated reducing agent to yield a compound of formula (II). Salts of the compound of formula (II) can be prepared by standard methods.

Compounds of formula (IIA) can be prepared as illustrated below in Reaction Scheme 17A wherein PG is an oxygen-protecting group, preferably optionally substituted benzyl; R² is selected to form a compound of formula (IIF) upon treatment with the compound of formula (IID), followed by cyclization, and is selected, but is not limited to, from the following radicals wherein the

line in the following represents the

bond between R² and the OR group in compounds of formula (IIE):

where each Y is halo; R is H, C₂-C₅acyl or an oxygen-protecting group; and R¹¹, R¹² and R¹³ are as defined above in the Summary of the Invention for the compounds of formula (II):

In general, the compounds of formula (IIA) are prepared in Reaction Scheme 17A by first treating a compound of formula (IID) with a compound of formula (IIE) in an aprotic solvent, such as toluene, dichloromethane, or ethyl acetate, followed by the treatment with an cyclizing agent, such as a C₂-C₅acyl halide or C₂-C₅acyl anhydride, at temperatures of between about 0° C. to reflux temperature, preferably at reflux temperature, to form a compound of formula (IIF). Alternatively, a compound of formula (IID) is first treated with a compound of formula (IIE) in an aprotic solvent to yield a corresponding intermediate, which is then treated with a cyclizing agent to form compounds of formula (IIF). Compounds of formula (IIF) are then subjected to standard deprotection conditions known to one skilled in the art, such as hydrogenation in the presence of a catalyst under appropriate conditions, to form the compound of formula (IIA), which is isolated from the reaction mixture by standard isolation techniques.

The compounds of formula (II) can be prepared according to methods similar to those described above in Reaction Schemes 2-16 using the appropriate chiral starting material or chiral reagent. In particular, compounds of formula (II) having the following cis stereochemistry at positions 1 and 2 of the cyclohexyl ring may be prepared:

It is understood, however, that compounds of formula (II) having the following stereochemistry at positions 1 and 2 of the cyclohexyl ring:

can be prepared in a similar manner using the appropriate chiral starting material or chiral reagent.

The invention is further defined by reference to the following Synthetic Examples and Biological Examples, which describe the preparation of several exemplary embodiments of the compounds described herein and methods for their use. It will be apparent to the skilled artisan that many modifications, both to the materials and methods, may be practiced without departing from the scope of the invention.

SYNTHETIC EXAMPLE 1 Preparation of (1R,2R)-2-[(3R)-Hydroxypyrrolidinyl]-1-(3-Methoxy-4-D₃-Methoxyphenethoxy)Cyclohexane

A. Homo vanillyl alcohol (1.0 g, 5.95 mmol) was dissolved in anhydrous DME (25 mL) followed by the addition of cesium carbonate (3.87 g, 11.89 mmol). The mixture was stirred under argon for 1 h and deuterium iodomethane (1.29 g, 8.92 mmol, 555 μL) was added. The reaction mixture was refluxed for 2.5 h and concentrated. The residue dissolved in ethyl acetate and washed with sat. NaHCO₃, water and dried over MgSO₄, filtered, concentrated to give a light yellow oil (1.03 g, 93%); ¹H NMR (300 MHz, CDCl₃): δ 6.82-6.74 (m, 3H, aromatic), 3.86 (s, 3H, OCH₃), 3.82 (t, 2H), 2.79 (t, 2H), 1.47 (s, 1H).

B. To an oven dried round bottom flask (100 mL) charged with argon and cooled was added NaH (197 mg, 8.2 mmol). A solution of the yellow oil (690 mg, 4.09 mmol) in anhydrous DME (20 mL) was added slowly to the reaction mixture and stirred for 1 h, then a solution of (1R,2R)/(1S,2S)-1-[(3R)-benzyloxypyrrolidinyl]-2-chlorocyclohexane (1.0 g, 3.41 mmol) in DME (20 mL) was added and the resultant mixture was heated to 80-85° C. for 18 h. To the cooled mixture was added, 2M NaHCO₃(10 mL), water (30 mL) and ethyl acetate (40 mL). The organic layer was collected and washed with brine, dried over MgSO₄ and concentrated in vacuo to give (1R,2R)-2-[(3R)-Benzyloxypyrrolidinyl-1-(3-methoxy-4-d₃-methoxyphenethoxy)cyclohexane (1.4 g, 93% yield).

C. To a solution of (1R,2R)-2-[(3R)-Benzyloxypyrrolidinyl-1-(3-methoxy-4-d₃-methoxyphenethoxy)cyclohexane (1.3 g, 2.94 mmol) in absolute ethanol (40 mL) was added palladium, 10 wt. % activated carbon (520 mg), 6M HCl (2 mL). The resultant reaction mixture was stirred for 18 h under a positive hydrogen atmosphere. The reaction mixture was filtered through celite 545 and concentrated to give 1.06 g of (1R,2R)-2-[(3R)-Hydroxypyrrolidinyl-1-(3-methoxy-4-d₃-methoxyphenethoxy)cyclohexane (92.6%); ¹H NMR (300 MHz, DMSO-d₆) δ 10.9-10.34 (m, 1H, NH), 6.86-6.73 (m, 3H), 5.49 (s, 1H), 4.33 (s, 1H), 4 (q, 1H), 3.73 (s, 3H, OCH₃), 3.57-3.02 (m, 6H), 2.78 (d, 2H, J 5.06), 2.18-1.62 (m, 6H), 1.39-1.05 (m, 4H); MS (ES+) [M+H]⁺ 353.10.

SYNTHETIC EXAMPLE 2 Preparation of (1R,2R)-2-[(3R)-Hydroxypyrrolidinyl]-1-(3,4-Di-D₃-Methoxyphenethoxy)Cyclohexane

Following the same synthetic methodology as described above in Example 1, except that 3,4-dihydroxyphenethyl alcohol is used as the starting material, (1R,2R)-2-[(3R)-hydroxypyrrolidinyl]-1-(3,4-di-d₃-methoxyphenethoxy)cyclonehexane was prepared: ¹H NMR (300 MHz, CDCl₃) δ 6.77-6.74 (m, 3H), 4.21-4.16 (m, 1H), 3.83-3.67 (m, 1H), 3.58-3.50 (m, 1H), 3.04-2.90 (m, 1H), 2.83-2.77 (m, 3H), 2.71-2.60 (m, 1H), 2.50-2.42 (m, 2H), 2.05-1.84 (m, 3H), 1.72-1.60 (m, 3H), 1.37-1.19 (m, 4H); ¹³C NMR (300 MHz, CDCl₃) δ 148.70 (+), 147.40 (+), 131.80 (+), 120.71 (−), 112.36 (−), 111.16 (−), 79.28/79.14 (−), 70.92/70.59 (−), 69.59/69.47 (+), 63.80/63.69 (−), 59.78/59.58 (+), 50.62 (−), 49.07/48.70 (+), 36.34 (+), 34.29/34.08 (+), 29.13 (+), 27.26/27.18 (+), 23.54 (+), 23.05 (+); MS (ES+) [M+H]⁺ 356.2.

SYNTHETIC EXAMPLE 3 Preparation of (1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-D₄-Pyrrolidinyl]-1-(3,4-Dimethoxyphenethoxy)Cyclohexane

(1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-d₄-pyrrolidinyl]-1-(3,4-dimethoxyphenethoxy)cyclohexane was prepared by adding 476 mL of a solution of 1 M BD₃.THF via an additional funnel under nitrogen over a period of 30 mins to a cooled solution (0° C.) of (1R,2R)-2-[(3R)-2,5-dioxo-3-acetoxypyrrolidinyl]-1-(3,4-dimethoxyphenethoxy)cyclohexane (57 g) in of anhydrous THF (200 mL). The reaction mixture was heated to 70° C.-75° C. (oil bath temperature) under nitrogen and stirred for 2 hours. The reaction mixture was cooled to 0° C. To the cooled solution, MeOH was slowly added over a period of 15 minutes and concentrated to remove solvent to a volume of approximately 150 mL. MeOH—HCl (380 mL) was added via addition funnel over a period of 15 min and then heated to 70° C.-75° C. (oil bath temperature) for 1 hour. The reaction mixture was then cooled to ambient temperature and concentrated under reduced pressure to provide of (1R,2R)-2-[(3R)-hydroxy-2,2,5,5-d₄-pyrrolidinyl]-1-(3,4-dimethoxyphenethoxy)cyclohexane hydrochloride (54 g).

SYNTHETIC EXAMPLE 4 Preparation of (1R,2R)-1(2-[2-(4-Benzyloxy-3-Methoxyphenyl)Ethoxy]Cyclohexyl)-(3R)-2,2,5,5-D₄-Pyrrolidinyl-3-Ol

BD₃.THF (459 mL) was added via addition funnel under nitrogen over a period of 45 minutes to a 0° C. solution of (1R,2R)-2-[(3R)-2,5-dioxo-3-Acetoxypyrrolidinyl]-1-(3-methoxy-4-ophenethoxy)cyclohexane (65 g) in anhydrous THF (220 mL). The reaction mixture was heated to 70° C.-75° C. (oil bath temperature) under nitrogen for 1 hour. The reaction mixture was then cooled to 0° C. and MeOH (50 mL) was added dropwise over a period of 30 minutes. The resultant reaction mixture was concentrated to a volume of approximately 150 mL to remove solvents. A solution of MeOH—HCl (370 mL) was added dropwise to the concentrated solution at 0° C. over a period of 30 min. The resulting reaction mixture was heated to reflux at 70° C.-75° C. for 1 hour and then allowed to cool to ambient temperature. The ambient temperature mixture was concentrated under reduced pressure to provide (1R,2R)-1(2-[2-(4-benzyloxy-3-methoxyphenyl)ethoxy]cyclohexyl)-(3R)-2,2,5,5-d₄-pyrrolidin-3-ol hydrochloride (61.13 g).

SYNTHETIC EXAMPLE 5 Preparation of (1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-D₄-Pyrrolidinyl]-1-(3-Methoxy-4-Hydroxyphenethoxy)Cyclohexane

(1R,2R)-1(2-[2-(4-benzyloxy-3-methoxyphenyl)ethoxy]cyclohexyl)-(3R)-2,2,5,5-d₄-pyrrolidin-3-ol (57 g) was dissolved in MeOH (250 mL). To the solution was added 5.7 g of Pd/C (loading 10% wt. supported activated carbon) in small portions while maintaining a nitrogen atmosphere throughout the reaction mixture. Using a Parr hydrogenator, a parr bottle containing the reaction mixture was evacuated and backfilled with hydrogen gas and repeated four times. Hydrogen pressure (60 psi) was then applied and the reaction vessel was shaken for 18 hours at ambient temperature. The reaction mixture was then filtered through a Celite™ pad with MeOH and the Pd/C was further washed with 50 mL of MeOH. The combined filtrates were concentrated under reduced pressure and then dried in vacuo to (1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-d₄-pyrrolidinyl]-1-(3-methoxy-4-hydroxyphenethoxy)cyclohexane hydrochloride (45 g).

SYNTHETIC EXAMPLE 5A Preparation of (1R,2R)-2-[(3R)-Hydroxypyrrolidinyl-1-(3,4-Dimethoxy-2,5,6-D₃-Phenethoxy)Cyclohexane

To a solution of (1R,2R)-2-[(3R)-hydroxypyrrolidinyl-1-(3,4-dimethoxyphenethoxy)cyclohexane hydrochloride (0.6 g, 1.6 mmol) in D₂O (2.0 mL, 99% D enrichment) was added Amberlyst 15 ion-exchange resin (0.6 g, Sigma-Aldrich, CAS # 39389-20-3). The mixture was heated in a sealed vessel for 24 h. On completion, the vessel was cooled, and the solution was filtered to remove the resin and washed with H₂O (2×5 mL). To the filtered solution was added a brine solution (15 mL) and the aqueous solution was extracted with CH₂Cl₂ (4×10 mL). The combined organic extracts were dried (MgSO₄), filtered, and concentrated under reduced pressure to obtain a foamy solid (0.5 g), which was further recrystallized from isopropyl alcohol to give (1R,2R)-2-[(3R)-hydroxypyrrolidinyl-1-(3,4-dimethoxy-2,5,6-d₃-phenethoxy)cyclohexane hydrochloride as a white solid (0.4 g). R_(f)=0.51 (1:1, v/v, EtOAc:MeOH with 5% IPrNH₂); MS (ES) Found=351.1 [M]⁺, 352.1 [M]⁺, 353.1 [M]⁺ (ratio ˜66%:100%:33% by MS).

SYNTHETIC EXAMPLE 6 Compounds of Formula (I)

Using the methods described in the above Reaction Schemes and Synthetic Examples, the following representative compounds of formula (I), where D is deuterium and an asterisk (*) represents a carbon wherein two deuterium atoms are attached, can be prepared: # Compound Chemical name 1

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,5,5-d₄-pyrrolidinyl]-1-(3,4- dimethoxyphenethoxy)cyclohexane 2

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,5,5-d₄-pyrrolidinyl]-1-(3,4- dimethoxyphen-2,2-d₂- ethoxy)cyclohexane 3

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,5,5-d₄-pyrrolidinyl]-1-(3,4- dimethoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 4

(1R,2R/1S,2S)-2-[(3R/3S)- Hydroxypyrrolidinyl]-1-(3,4- dimethoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 5

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,5,5-d₄-pyrrolidinyl]-1-(3-methoxy-4- d₃-methoxyphenethoxy)cyclohexane 6

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,5,5-d₄-pyrrolidinyl]-1-(3-methoxy-4- d₃-methoxyphen-1,1-d₂- ethoxy)cyclohexane 7

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy-2,2- d₂-pyrrolidinyl]-1-(3-methoxy-4-d₃- methoxyphen-1,1-d₂- ethoxy)cyclohexane 8

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy-5,5- d₂-pyrrolidinyl]-1-(3-methoxy-4-d₃- methoxyphen-1,1-d₂- ethoxy)cyclohexane 9

(1R,2R/1S,2S)-2-[(3R/3S)- Hydroxypyrrolidinyl]-1-(3,4-di-d₃- methoxyphen-1,1-d₂- ethoxy)cyclohexane 10

(1R,2R/1S,2S)-2-[(3R/3S)- Hydroxypyrrolidinyl]-1-(3,4-di-d₃- methoxyphenethoxy)cyclohexane 11

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,5,5-d₄-pyrrolidinyl]-1-(3,4-di-d₃- methoxyphen-1,1-d₂- ethoxy)cyclohexane 12

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,5,5-d₄-pyrrolidinyl]-1-(3,4-di-d₃- methoxphenethoxy)cyclohexane 13

(1R,2R/1S,2S)-2-[(3R/3S)- Hydroxypyrrolidinyl]-1-(3-methoxy-4-d₃- methoxyphen-2,2-d₂- ethoxy)cyclohexane 14

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,5,5-d₄-pyrrolidinyl]-1-(3-methoxy-4- d₃-methoxyphen-2,2-d₂- ethoxy)cyclohexane 15

(1R,2R/1S,2S)-2-[(3R/3S)- Hydroxypyrrolidinyl]-1-(3-d₃-methoxy-4- methoxyphen-1,1-d₂- ethoxy)cyclohexane 16

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,5,5-d₄-pyrrolidinyl]-1-(3-d₃-methoxy- 4-methoxyphen-1,1-d₂- ethoxy)cyclohexane 17

(1R,2R/1S,2S)-2-[(3R/3S)- Hydroxypyrrolidinyl]-1-(3-d₃-methoxy-4- methoxyphenethoxy)cyclohexane 18

(1R,2R/1S,2S)-2-[(3R/3S)- Hydroxypyrrolidinyl]-1-(3-methoxy-4-d₃- methoxyphenethoxy)cyclohexane 19

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,5,5-d₄-pyrrolidinyl]-1-(3-d₃-methoxy- 4-methoxyphenethoxy)cyclohexane 20

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 3,4,4-d₃-pyrrolidinyl]-1-(3,4- dimethoxyphen-1,1-d₂-ethoxy)cyclohexane 21

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3,4- dimethoxyphen-1,1-d₂-ethoxy)cyclohexane 22

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 3,4,4-d₃-pyrrolidinyl]-1-(3,4- dimethoxyphen-2,2-d₂- ethoxy)cyclohexane 23

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3,4- dimethoxyphen-2,2-d₂-ethoxy)cyclohexane 24

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 3,4,4-d₃-pyrrolidinyl]-1-(3-d₃-methoxy-4- methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 25

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3-d₃- methoxy-4-methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 26

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 3,4,4-d₃-pyrrolidinyl]-1-(3-methoxy-4-d₃- methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 27

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3- methoxy-4-d₃-methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 28

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 3,4,4-d₃-pyrrolidinyl]-1-(3-d₃-methoxy-4- methoxyphen-2,2-d₂- ethoxy)cyclohexane 29

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3-d₃- methoxy-4-methoxyphen-2,2-d₂- ethoxy)cyclohexane 30

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 3,4,4-d₃-pyrrolidinyl]-1-(3-methoxy-4-d₃- methoxyphen-2,2-d₂- ethoxy)cyclohexane 31

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3- methoxy-4-d₃-methoxyphen-2,2-d₂- ethoxy)cyclohexane 32

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 3,4,4-d₃-pyrrolidinyl]-1-(3-d₃-methoxy-4- methoxyphen-1,1-d₂- ethoxy)cyclohexane 33

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3-d₃- methoxy-4-methoxyphen-1,1-d₂- ethoxy)cyclohexane 34

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 3,4,4-d₃-pyrrolidinyl]-1-(3-methoxy-4-d₃-methoxyphen-1,1-d₂- ethoxy)cyclohexane 35

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3- methoxy-4-d₃-methoxyphen-1,1-d₂- ethoxy)cyclohexane 36

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,5,5-d₄-pyrrolidinyl]-1-(3-methoxy-4- hydroxyphenethoxy)cyclohexane 37

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,5,5-d₄-pyrrolidinyl]-1-(3-methoxy-4- ethoxy)cyclohexane 38

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,5,5-d₄-pyrrolidinyl]-1-(3-methoxy-4- hydroxyphen-2,2-d₂- ethoxy)cyclohexane 39

(1R,2R/1S,2S)-2-[(3R/3S)- Hydroxypyrrolidinyl]-1-(3-methoxy-4- hydroxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 40

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,5,5-d₄-pyrrolidinyl]-1-(3-methoxy-4- hydroxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 41

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3- methoxy-4- hydroxyphenethoxy)cyclohexane 42

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3- methoxy-4-hydroxyphen-2,2-d₂- ethoxy)cyclohexane 43

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3- methoxy-4-hydroxyphen-1,1-d₂- ethoxy)cyclohexane 44

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 3,4,4-d₃-pyrrolidinyl]-1-(3-methoxy-4- hydroxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 45

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 3,4,4-d₃-pyrrolidinyl]-1-(3-methoxy-4- hydroxyphen-2,2-d₂- ethoxy)cyclohexane 46

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 3,4,4-d₃-pyrrolidinyl]-1-(3-methoxy-4- hydroxyphen-1,1-d₂- ethoxy)cyclohexane 47

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 3,4,4-d₃-pyrrolidinyl]-1-(3-methoxy-4- hydroxyphenethoxy)cyclohexane 48

(1R,2R/1S,25)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3- methoxy-4-hydroxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 49

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,5,5-d₄-pyrrolidinyl]-1-(3-hydroxy-4- methoxyphenethoxy)cyclohexane 50

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,5,5-d₄-pyrrolidinyl]-1-(3-hydroxy-4- methoxyphen-1,1-d₂- ethoxy)cyclohexane 51

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,5,5-d₄-pyrrolidinyl]-1-(3-hydroxy-4- methoxyphen-2,2-d₂- ethoxy)cyclohexane 52

(1R,2R/1S,2S)-2-[(3R/3S)- Hydroxypyrrolidinyl]-1-(3-hydroxy-4- methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 53

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,5,5-d₄-pyrrolidinyl]-1-(3-hydroxy-4- methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 54

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3- hydroxy-4- methoxyphenethoxy)cyclohexane 55

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3- hydroxy-4-methoxyphen-2,2-d₂- ethoxy)cyclohexane 56

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3- hydroxy-4-methoxyphen-1,1-d₂- ethoxy)cyclohexane 57

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3- hydroxy-4-methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 58

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 3,4,4-d₃-pyrrolidinyl]-1-(3-hydroxy-4- methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 59

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 3,4,4-d₃-pyrrolidinyl]-1-(3-hydroxy-4- methoxyphen-2,2-d₂- ethoxy)cyclohexane 60

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 3,4,4-d₃-pyrrolidinyl]-1-(3-hydroxy-4- methoxyphen-1,1-d₂- ethoxy)cyclohexane 61

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 3,4,4-d₃-pyrrolidinyl]-1-(3-hydroxy-4- methoxyphenethoxy)cyclohexane 62

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3-d₃- methoxy-4-hydroxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 63

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3- hydroxy-4-d₃-methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 64

(1R,2R/1S,2S)-2-[(3R/3S)-Hydroxy- 2,2,3,4,4,5,5-d₇-pyrrolidinyl]-1-(3,4-di- d₃-methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 65

(1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-d₄- pyrrolidinyl]-1-(3,4-dimethoxyphen-2,2- d₂-ethoxy)cyclohexane 66

(1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-d₄- pyrrolidinyl]-1-(3,4-dimethoxyphen- 1,1,2,2-d₄-ethoxy)cyclohexane 67

(1R,2R)-2-[(3R)-Hydroxypyrrolidinyl]-1- (3,4-dimethoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 68

(1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-d₄- pyrrolidinyl]-1-(3-methoxy-4-d₃- methoxyphenethoxy)cyclohexane 69

(1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-d₄- pyrrolidinyl]-1-(3-methoxy-4-d₃- methoxyphen-1,1-d₂- ethoxy)cyclohexane 70

(1R,2R)-2-[(3R)-Hydroxy-2,2-d₂- pyrrolidinyl]-1-(3-methoxy-4-d₃- methoxyphen-1,1-d₂- ethoxy)cyclohexane 71

(1R,2R)-2-[(3R)-Hydroxy-5,5-d₂- pyrrolidinyl]-1-(3-methoxy-4-d₃- methoxyphen-1,1-d₂- ethoxy)cyclohexane 72

(1R,2R)-2-[(3R)-Hydroxypyrrolidinyl]-1- (3,4-di-d₃-methoxyphen-1,1-d₂- ethoxy)cyclohexane 73

(1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-d₄- pyrrolidinyl]-1-(3,4-di-d₃-methoxyphen- 1,1-d₂-ethoxy)cyclohexane 74

(1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-d₄- pyrrolidinyl]-1-(3,4-di-d₃- methoxphenethoxy)cyclohexane 75

(1R,2R)-2-[(3R)-Hydroxypyrrolidinyl]-1- (3-methoxy-4-d₃-methoxyphen-2,2-d₂- ethoxy)cyclohexane 76

(1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-d₄- pyrrolidinyl]-1-(3-methoxy-4-d₃- methoxyphen-2,2-d₂- ethoxy)cyclohexane 77

(1R,2R)-2-[(3R)-Hydroxypyrrolidinyl]-1- (3-d₃-methoxy-4-methoxyphen-1,1-d₂- ethoxy)cyclohexane 78

(1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-d₄- pyrrolidinyl]-1-(3-d₃-methoxy-4- methoxyphen-1,1-d₂- ethoxy)cyclohexane 79

(1R,2R)-2-[(3R)-Hydroxypyrrolidinyl]-1- (3-d₃-methoxy-4- methoxyphenethoxy)cyclohexane 80

(1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-d₄- pyrrolidinyl]-1-(3-d₃-methoxy-4- methoxyphenethoxy)cyclohexane 81

(1R,2R)-2-[(3R)-Hydroxy-3,4,4-d₃- pyrrolidinyl]-1-(3,4-dimethoxyphen-1,1- d₂-ethoxy)cyclohexane 82

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3,4-dimethoxyphen- 1,1-d₂-ethoxy)cyclohexane 83

(1R,2R)-2-[(3R)-Hydroxy-3,4,4-d₃- pyrrolidinyl]-1-(3,4-dimethoxyphen-2,2- d₂-ethoxy)cyclohexane 84

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3,4-dimethoxyphen- 2,2-d₂-ethoxy)cyclohexane 85

(1R,2R)-2-[(3R)-Hydroxy-3,4,4-d₃- pyrrolidinyl]-1-(3-d₃-methoxy-4- methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 86

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3-d₃-methoxy-4- methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 87

(1R,2R)-2-[(3R)-Hydroxy-3,4,4-d₃- pyrrolidinyl]-1-(3-methoxy-4-d₃- methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 88

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3-methoxy-4-d₃- methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 89

(1R,2R)-2-[(3R)-Hydroxy-3,4,4-d₃- pyrrolidinyl]-1-(3-d₃-methoxy-4- methoxyphen-2,2-d₂- ethoxy)cyclohexane 90

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3-d₃-methoxy-4- methoxyphen-2,2-d₂- ethoxy)cyclohexane 91

(1R,2R)-2-[(3R)-Hydroxy-3,4,4-d₃- pyrrolidinyl]-1-(3-methoxy-4-d₃- methoxyphen-2,2-d₂- ethoxy)cyclohexane 92

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3-methoxy-4-d₃- methoxyphen-2,2-d₂- ethoxy)cyclohexane 93

(1R,2R)-2-[(3R)-Hydroxy-3,4,4-d₃- pyrrolidinyl]-1-(3-d₃-methoxy-4- methoxyphen-1,1-d₂- ethoxy)cyclohexane 94

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3-d₃-methoxy-4- methoxyphen-1,1-d₂- ethoxy)cyclohexane 95

(1R,2R)-2-[(3R)-Hydroxy-3,4,4-d₃- pyrrolidinyl]-1-(3-methoxy-4-d₃- methoxyphen-1,1-d₂- ethoxy)cyclohexane 96

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3-methoxy-4-d₃- methoxyphen-1,1-d₂- ethoxy)cyclohexane 97

(1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-d₄- pyrrolidinyl]-1-(3-methoxy-4- hydroxyphen-1,1-d₂- ethoxy)cyclohexane 98

(1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-d₄- pyrrolidinyl]-1-(3-methoxy-4- hydroxyphen-2,2-d₂- ethoxy)cyclohexane 99

(1R,2R)-2-[(3R)-Hydroxypyrrolidinyl]-1- (3-methoxy-4-hydroxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 100

(1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-d₄- pyrrolidinyl]-1-(3-methoxy-4- hydroxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 101

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3-methoxy-4- hydroxyphenethoxy)cyclohexane 102

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3-methoxy-4- hydroxyphen-2,2-d₂- ethoxy)cyclohexane 103

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3-methoxy-4- hydroxyphen-1,1-d₂- ethoxy)cyclohexane 104

(1R,2R)-2-[(3R)-Hydroxy-3,4,4-d₃- pyrrolidinyl]-1-(3-methoxy-4- hydroxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 105

(1R,2R)-2-[(3R)-Hydroxy-3,4,4-d₃- pyrrolidinyl]-1-(3-methoxy-4- hydroxyphen-2,2-d₂- ethoxy)cyclohexane 106

(1R,2R)-2-[(3R)-Hydroxy-3,4,4-d₃- pyrrolidinyl]-1-(3-methoxy-4- hydroxyphen-1,1-d₂- ethoxy)cyclohexane 107

(1R,2R)-2-[(3R)-Hydroxy-3,4,4-d₃- pyrrolidinyl]-1-(3-methoxy-4- hydroxyphenethoxy)cyclohexane 108

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3-methoxy-4- hydroxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 109

(1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-d₄- pyrrolidinyl]-1-(3-hydroxy-4- methoxyphenethoxy)cyclohexane 110

(1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-d₄- pyrrolidinyl]-1-(3-hydroxy-4- methoxyphen-1,1-d₂- ethoxy)cyclohexane 111

(1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-d₄- pyrrolidinyl]-1-(3-hydroxy-4- methoxyphen-2,2-d₂- ethoxy)cyclohexane 112

(1R,2R)-2-[(3R)-Hydroxypyrrolidinyl]-1- (3-hydroxy-4-methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 113

(1R,2R)-2-[(3R)-Hydroxy-2,2,5,5-d₄- pyrrolidinyl]-1-(3-hydroxy-4- methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 114

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3-hydroxy-4- methoxyphenethoxy)cyclohexane 115

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3-hydroxy-4- methoxyphen-2,2-d₂- ethoxy)cyclohexane 116

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3-hydroxy-4- methoxyphen-1,1-d₂- ethoxy)cyclohexane 117

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3-hydroxy-4- methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 118

(1R,2R)-2-[(3R)-Hydroxy-3,4,4-d₃- pyrrolidinyl]-1-(3-hydroxy-4- methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 119

(1R,2R)-2-[(3R)-Hydroxy-3,4,4-d₃- pyrrolidinyl]-1-(3-hydroxy-4- methoxyphen-2,2-d₂- ethoxy)cyclohexane 120

(1R,2R)-2-[(3R)-Hydroxy-3,4,4-d₃- pyrrolidinyl]-1-(3-hydroxy-4- methoxyphen-1,1-d₂- ethoxy)cyclohexane 121

(1R,2R)-2-[(3R)-Hydroxy-3,4,4-d₃- pyrrolidinyl]-1-(3-hydroxy-4- methoxyphenethoxy)cyclohexane 122

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3-d₃-methoxy-4- hydroxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 123

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3-hydroxy-4-d₃- methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane 124

(1R,2R)-2-[(3R)-Hydroxy-2,2,3,4,4,5,5- d₇-pyrrolidinyl]-1-(3,4-di-d₃- methoxyphen-1,1,2,2-d₄- ethoxy)cyclohexane

BIOLOGICAL EXAMPLE 1 Determining the Concentration of a Compound of Formula (1) or a Compound of Formula (2) in a Biological Matrix

The following describes an assay wherein compounds of the invention were used to determine the concentration of a compound of formula (1) in a biological matrix. The same assay may be used to determine the concentration of a compound of formula (2) in a biological matrix.

Stock solutions of 3-pyrrolidinol, 1-[(1R,2R)-2-[2-(3,4-dimethoxyphenyl)ethoxy]-cyclohexyl]-, hydrochloride, 3(R) (hereinafter “R-StS”) and 3-pyrrolidinol, 1-[(1R,2R)-2-[2-(3,4-dimethoxyphenyl)ethoxy]cyclohexyl]-, hydrochloride, 3(S) (hereinafter “S-StS”) (compounds of formula (1)) were prepared separately in water at 1 mg/mL for preparation of standard curve and QC samples. The concentrations of the stock solutions were corrected for chemical potency and molecular weight of the free base. Aliquots of each stock solution were mixed together to prepare a working solution (WS1) containing 60 μg/mL each of R-StS and S-StS. An internal standard solution (1S) containing (1R,2R)-2-[(3R)-hydroxy-2,2,5,5-d₄-pyrrolidinyl]-1-(3,4-dimethoxyphenethoxy)cyclohexane hydrochloride and (1R,2R)-2-[(3R)-hydroxy-2,2,5,5-d₄-pyrrolidinyl]-1-(3-methoxy-4-hydroxyphenethoxy)cyclohexane hydrochloride was prepared at 0.5 μg/mL in water.

A series of standard spiking solutions (SpS) were prepared according to Table 1. TABLE 1 Volume of Core Volume Concen- Concen- Core Solution of Total tration tration Solution Used Water Volume of R-StS of S-StS SpS Used (μL) (μL) (μL) (ng/mL) (ng/mL) SpS1 ws1 200 3800 4000 2999 3001 SpS2 ws1 150 3850 4000 2249 2251 SpS3 ws1 90 3910 4000 1350 1350 SpS4 ws1 60 3940 4000 900 900 SpS5 SpS1 600 3400 4000 450 450 SpS6 SpS1 240 3760 4000 180 180 SpS7 SpS1 120 3880 4000 90.0 90.0 SpS8 SpS1 60 3940 4000 45.0 45.0 SpS9 SpS6 667 3333 4000 30.0 30.0 SpS10 SpS6 333 3667 4000 15.0 15.0 SpS11 SpS6 111 3889 4000 4.99 5.00 SpS12 SpS6 56 3944 4000 2.52 2.52

The standard spiking solutions (SpS) were then spiked into blank rat plasma together with internal standard solution (1S) to obtain standard calibrators (STD) according to Table 2. TABLE 2 Blank Final Concentration Standard Plasma SpS IS in Rat Plasma Spiking Volume Volume Volume (ng/mL of plasma) STD Solution (μL) (μL) (μL) R-StS S-StS STD1 SpS1 20 40 50 5998 6002 STD2 SpS2 20 40 50 4499 4501 STD3 SpS3 20 40 50 2699 2701 STD4 SpS4 20 40 50 1800 1800 STD5 SpS5 20 40 50 900 900 STD6 SpS6 20 40 50 360 360 STD7 SpS7 20 40 50 180 180 STD8 SpS8 20 40 50 90.0 90.0 STD9 SpS9 20 40 50 60.0 60.0 STD10 SpS10 20 40 50 30.0 30.0 STD11 SpS11 20 40 50 9.99 9.99 STD12 SpS12 20 40 50 5.04 5.04

Quality control spiking solutions (QCS) were prepared according to Table 3. TABLE 3 Volume Volume Concen- Concen- Core of Core of Total tration tration Solution solution Water Volume of R-StS of S-StS QCS Used (μL) (μL) (μL) (ng/mL) (n/mL) QCS1 ws1 200 3800 4000 2999 3001 QCS2 ws1 150 3850 4000 2249 2251 QCS4 ws1 60 3940 4000 900 900 QCS6 QCS1 240 3760 4000 180 180 QCS10 QCS6 333 3667 4000 15.0 15.0

The QC spiking solutions were then spiked into blank rat plasma together with internal standard to obtain QC samples according to Table 4. QC samples were prepared in six replicates for each level. TABLE 4 Blank Final concentration Standard Plasma Volume IS in Rat Plasma Spiking Volume of QCS Volume (ng/mL of plasma) QC Solution (μL) (μL) (μL) R-StS S-StS H QCS2 20 40 50 4499 4501 M QCS4 20 40 50 1800 1800 L QCS6 20 40 50 360 360 LL QCS10 20 40 50 30.0 30.0 Extraction Procedure

Thaw blank plasma at room temperature. Transfer 20 μL of blank plasma to 1 mL 96-deep well plate. Add 40 μL of spiking standard solution or spiking QC solution (or water for a test sample). Add 50 μL of internal standard solution. Lower pH to approximately 2.0 by adding 50 μL of 2% phosphoric acid and vortex sample mixture. Add 200 μL of methanol to a microelution plate (comprising a mixture cation exchange/reverse phase column) and apply vacuum. Add 200 μL of water to the microelution plate and apply vacuum. Transfer samples to the microelution plate and apply vacuum. Add 200 μL of 2% formic acid to the microelution plate and apply vacuum. Add 200 μL of methanol to a microelution plate and apply vacuum. Replace waste plate with 350 μL 96-deep well collection plate. Add 100 μL of 40/60 (v/v) acetonitrile/isopropanol in 5% ammonium hydroxide and apply vacuum. Evaporate samples under N₂ stream to dryness (10 mins). Add 50 μL of mobile phase to reconstitute eluted sample for analysis. Vortex and sonicate reconstituted sample for 1 min. Seal plate with plastic mat and inject samples.

The LC/MS/MS conditions used to determine the concentration of the compounds of formula (1) in the samples are set out in Table 5: TABLE 5 Column temperature 26° C. Sample temperature 10° C. Mobile phase Isocratic, 13:87 (v/v) of 0.1% formic acid in methanol to 0.1% formic acid in water Flowrate 0.35 mL/min Injection volume 10 μL Runtime 18 min MS/MS acquisition ESI, +ve MRM mode

The above assay demonstrated that the use of the compounds of the invention as internal standards was effective in determining the concentration of compounds of formula (1) in a biological matrix, such as plasma.

BIOLOGICAL EXAMPLE 2 Assessment of Antiarrhythmic Efficacy

Antiarrhythmic efficacy may be assessed by investigating the effect of a compound of the invention on the incidence of cardiac arrhythmias in anesthetized rats subjected to coronary artery occlusion. Rats weighing 200-300 g are subjected to preparative surgery and assigned to groups in a random block design. In each case, the animal is anesthetized with pentobarbital during surgical preparation. The left carotid artery is cannulated for measurement of mean arterial blood pressure and withdrawal of blood samples. The left jugular vein is also cannulated for injection of drugs. The thoracic cavity is opened and a polyethylene occluder loosely placed around the left anterior descending coronary artery. The thoracic cavity is then closed. An ECG is recorded by insertion of electrodes placed along the anatomical axis of the heart. In a random and double-blind manner, an infusion of vehicle or the compound to be tested is given about 15 min post-surgery. After 5 minutes infusion, the occluder is pulled so as to produce a coronary artery occlusion. ECG, arrhythmias, blood pressure, heart rate and mortality are monitored for 15 minutes after occlusion. Arrhythmias are recorded as ventricular tachycardia (VT) and ventricular fibrillation (VF) and scored according to Curtis, M. J. and Walker, M. J. A., Cardiovasc. Res. 22:656 (1988).

Rats are excluded from the study if they did not exhibit pre-occlusion serum potassium concentrations within the range of 2.9-3.9 mM. Occlusion is associated with increases in R-wave height and “S-T” segment elevation; and an occluded zone (measured after death by cardiogreen dye perfusion) in the range of 25%-50% of total left-ventricular weight.

Results of the test compounds may be expressed as values of a given infusion rate in micromol/kg/min. (ED₅₀AA) which will reduce the arrhythmia score in treated animals to 50% of that shown by animals treated only with the vehicle in which the test compound(s) is dissolved.

BIOLOGICAL EXAMPLE 3 Measurement of Cardiovascular and Behavioral Effects

Preparative surgery is performed in Sprague Dawley rats weighing 200-300 g and anaesthetized with 65 mg/kg (i.p.) pentobarbital. The femoral artery and vein are cannulated using polyethylene (PE)-10 tubing. Prior to surgery, this PE-10 tubing had been annealed to a wider gauge (PE-50) tubing for externalization. The cannulated PE-10/PE-50 tubing is passed through a trocar and exteriorised together with three (lead 11) limb ECG leads (see below). The trocar is threaded under the skin of the back and out through a small incision at the mid-scapular region. A ground ECG electrode is inserted subcutaneously using a 20 gauge needle with the lead wire threaded through it. To place the other ECG electrodes, a small incision is made in the anterior chest region over the heart and ECG leads are inserted into the subcutaneous muscle layer in the region of the heart using a 20 gauge needle. Other ECG leads are inserted into the subcutaneous muscle layer in the region near the base of the neck and shoulder (right side). The animal is returned to a clean recovery-cage with free access to food and water. The treatment and observational period for each animal commenced after a 24-hour recovery period.

A 15 min observational period is recorded followed by the intravenous infusion regime of the test compound at an initial dose of 2.0 μmol/kg/min (at 1 mL/hr). This rate is doubled every 5 minutes until one of the following effects is observed:

-   -   a) partial or complete convulsions     -   b) severe arrhythmias     -   c) bradycardia below 120 beats/min     -   d) hypotension below 50 mmHg     -   e) the dose exceeds 32 times the initial starting dose (i.e. 64         μmol/kg/min).

Blood pressure (BP), heart rate (HR) and ECG variables are continuously recorded while behavioral responses are also monitored and the total accumulative drug dose and drug infusion rate at which the response (such as convulsion, piloerection, ataxia, restlessness, compulsive chewing, lip-smacking, wet dog shake etc.) occurred are recorded.

Estimates of plasma concentrations of the test compound are determined by removing a 0.5 mL blood sample at the end of the experiment. Blood samples are centrifuged for 5 min at 4600×g and the plasma decanted. Brain tissue samples are also extracted and kept frozen (−20° C.) along with the plasma samples for chemical analysis.

Electrocardiograph (ECG) parameters: PR, QRS, QT₁ (peak of T-wave), QT₂ (midpoint of T-wave deflection) and hemodynamic parameters: BP and HR are analyzed using the automated analysis function in LabView (National Instruments) with a customized autoanalysis software (Nortran Pharmaceuticals). The infused dose producing 25% from control (D₂₅) for all recorded ECG variables is determined.

Results of the tests can be expressed as D₂₅ (micromol/kg) which are the doses required to produce a 25% increase in the ECG parameter measured. The increases in P-R interval and QRS interval indicate cardiac sodium channel blockade while the increase in Q-T interval indicates cardiac potassium channel blockade.

BIOLOGICAL EXAMPLE 4 Electrophysiological Test (In Vivo)

Male Sprague-Dawley rats weighing between 250-350 g are used. They are randomly selected from a single group and anesthetized with pentobarbital (65 mg/kg, ip.) with additional anesthetic given if necessary.

The trachea is cannulated and the rat is artificially ventilated at a stroke volume of 10 mL/kg, 60 strokes/minute. The right external jugular vein and the left carotid artery are cannulated for intravenous injections of compounds and blood pressure (BP) recording, respectively.

Needle electrodes are subcutaneously inserted along the suspected anatomical axis (right atrium to apex) of the heart for ECG measurement. The superior electrode is placed at the level of the right clavicle about 0.5 cm from the midline, while the inferior electrode is placed on the left side of the thorax, 0.5 cm from the midline and at the level of the ninth rib.

Two Teflon-coated silver electrodes are inserted through the chest wall using 27 G needles as guides and implanted in the epicardium of left ventricle (4-5 mm apart). Square pulse stimulation is provided by a stimulator controlled by a computer. In-house programmed software is used to determine the following: threshold current (iT) for induction of extra systoles, maximum following frequency (MFF), effective refractory period (ERP) and ventricular flutter threshold (VTt). Briefly, iT is measured as the minimal current (in μA) of a square wave stimulus required to capture and pace the heart at a frequency of 7.5 Hz and a pulse width of 0.5 msec; ERP is the minimum delay (in msec) for a second stimulus required to cause an extra systole with the heart entrained at a frequency of 7.5 Hz (1.5×iT and 0.2 msec pulse width), MFF is the maximum stimulation frequency (in Hz) at which the heart is unable to follow stimulation (1.5×iT and 0.2 msec pulse width); Vrt is the minimum pulse current (in μA) to evoke a sustained episode of VT (0.2 msec pulse width and 50 Hz) (Howard, P. G. and Walker, M. J. A., Proc. West. Pharmacol. Soc. 33:123-127 (1990)).

Blood pressure (BP) and electrocardiographic (ECG) parameters are recorded and analyzed using LabView (National Instruments) with a customized autoanalysis software (Nortran Pharmaceuticals Inc.) to calculate mean BP (mmHg, 2/3 diastolic+1/3 systolic blood pressure), HR (bpm, 60/R—R interval); PR (msec, the interval from the beginning of the P-wave to the peak of the R-wave), QRS (msec, the interval from the beginning of the R-wave due to lack of Q wave in rat ECG, to the peak of the S-wave), QT (msec, the interval from the beginning of the R-wave to the peak of the T-wave).

The initial infusion dose is chosen based on a previous toxicology study of the test compound in conscious rats. This is an infusion dose that did not produce a 10% change from pre-drug levels in haemodynamic or ECG parameters.

The animal is left to stabilize prior to the infusion treatment according to a predetermined random and blind table. The initial infusion treatment is started at a rate of 0.5 mL/hr/300 g (i.e., 0.5 μmol/kg/min). Each infusion dose is doubled (in rate) every 5 minutes. All experiments are terminated at 32 mL/hr/300 g (i.e., 32 μmol/kg/min). Electrical stimulation protocols are initiated during the last two minutes of each infusion level.

Responses to test compounds are calculated as percent changes from pre-infusion values; this normalization is used to reduce individual variation. The mean values of BP and ECG parameters at immediately before the electrical stimulation period (i.e., 3 min post-infusion) are used to construct cumulative dose-response curves. Data points are fit using lines of best fit with minimum residual sum of squares (least squares; SlideWrite program; Advanced Graphics Software, Inc.). D₂₅'s (infused dose that produced 25% change from pre-infusion value) are interpolated from individual cumulative dose-response curves and used as indicators for determining the potency of compounds of the present invention.

While the invention has been described and illustrated with reference to certain particular embodiments thereof, those skilled in the art will appreciate that various adaptations, changes, modifications, substitutions, deletions or additions of procedures and protocols may be made without departing from the spirit and scope of the invention. It is intended, therefore, that the invention be defined by the scope of the claims which follow and that such claims be interpreted as broadly as is reasonable to one skilled in the art. 

1. A compound of formula (I):

wherein: R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R¹¹, R¹², R¹³, R¹⁴, R¹⁵ and R¹⁶ are each independently hydrogen or deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; and at least one deuterium is present; as an isolated stereoisomer or as a mixture of stereoisomers; or a pharmaceutically acceptable salt thereof.
 2. The compound of claim 1 wherein: R¹ and R² are both hydrogen or are both deuterium; R³ and R⁴ are both hydrogen or are both deuterium; R⁵ and R⁶ are both hydrogen or are both deuterium; R⁷ and R⁸ are both hydrogen or are both deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; R¹¹ is hydrogen or deuterium; R¹² and R¹³ are both hydrogen or are both deuterium; and R¹⁴, R¹⁵, and R¹⁶ are all hydrogen or all deuterium.
 3. The compound of claim 1 wherein: R¹ and R² are both hydrogen or are both deuterium; R³ and R⁴ are both hydrogen or are both deuterium; R⁵ and R⁵ are both deuterium; R⁷ and R⁸ are both hydrogen or are both deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; R¹¹ is hydrogen or deuterium; R¹² and R¹³ are both hydrogen or are both deuterium; and R¹⁴, R¹⁵, and R¹⁶ are all hydrogen or all deuterium.
 4. The compound of claim 1 wherein: R¹ and R² are both hydrogen or are both deuterium; R³ and R⁴ are both hydrogen or are both deuterium; R⁵ and R⁶ are both hydrogen or are both deuterium; R⁷ and R⁸ are both deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; R¹¹ is hydrogen or deuterium; R¹² and R¹³ are both hydrogen or are both deuterium; and R¹⁴, R¹⁵, and R¹⁶ are all hydrogen or all deuterium.
 5. The compound of claim 1 wherein: R¹ and R² are both deuterium; R³ and R⁴ are both deuterium; R⁵ and R⁶ are both hydrogen or are both deuterium; R⁷ and R⁸ are both hydrogen or are both deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; R¹¹ is hydrogen or deuterium; R¹² and R¹³ are both hydrogen or are both deuterium; and R¹⁴, R¹⁵, and R¹⁶ are all hydrogen or all deuterium.
 6. The compound of claim 1 wherein: R¹ and R² are both hydrogen or are both deuterium; R³ and R⁴ are both hydrogen or are both deuterium; R⁵ and R⁶ are both hydrogen or are both deuterium; R⁷ and R⁸ are both hydrogen or are both deuterium; R⁹ is —OCD₃; R¹⁰ is hydroxy, methoxy or —OCD₃; R¹¹ is hydrogen or deuterium; R¹² and R¹³ are both hydrogen or are both deuterium; and R¹⁴, R¹⁵, and R¹⁶ are all hydrogen or all deuterium.
 7. The compound of claim 1 wherein: R¹ and R² are both hydrogen or are both deuterium; R³ and R⁴ are both hydrogen or are both deuterium; R⁵ and R⁶ are both hydrogen or are both deuterium; R⁷ and R⁸ are both hydrogen or are both deuterium; R⁹ is hydroxy, methoxy or —OCD₃; R¹⁰ is —OCD₃; R¹¹ is hydrogen or deuterium; R¹² and R¹³ are both hydrogen or are both deuterium; and R¹⁴, R¹⁵, and R¹⁶ are all hydrogen or all deuterium.
 8. The compound of claim 1 wherein: R¹ and R² are both hydrogen or are both deuterium; R³ and R⁴ are both hydrogen or are both deuterium; R⁵ and R⁶ are both hydrogen or are both deuterium; R⁷ and R⁸ are both hydrogen or are both deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; R¹¹ is deuterium; R¹² and R¹³ are both hydrogen or are both deuterium; and R¹⁴, R¹⁵, and R¹⁶ are all hydrogen or all deuterium.
 9. The compound of claim 1 wherein: R¹ and R² are both hydrogen or are both deuterium; R³ and R⁴ are both hydrogen or are both deuterium; R⁵ and R⁶ are both hydrogen or are both deuterium; R⁷ and R⁸ are both hydrogen or are both deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; R¹¹ is hydrogen or deuterium; R¹² and R¹³ are both deuterium; and R¹⁴, R¹⁵, and R¹⁶ are all hydrogen or all deuterium.
 10. A pharmaceutical composition comprising a pharmaceutically acceptable excipient and a compound of formula (I):

wherein: R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R¹¹, R¹², R¹³, R¹⁴, R¹⁵ and R¹⁶ are each independently hydrogen or deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; and at least one deuterium is present; as an isolated stereoisomer or as a mixture of stereoisomers; or a pharmaceutically acceptable salt thereof.
 11. A method of treating arrhythmia in a human, wherein the method comprises administering to the human in need thereof a therapeutically effective amount of a compound of formula (I):

wherein: R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R¹¹, R¹², R¹³, R¹⁴, R¹⁵ and R¹⁶ are each independently hydrogen or deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; and at least one deuterium is present; as an isolated stereoisomer or as a mixture of stereoisomers; or a pharmaceutically acceptable salt thereof.
 12. A method of preparing a compound of formula (I):

wherein: R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R¹¹, R¹² and R¹³ are each independently hydrogen or deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; R¹⁴, R¹⁵ and R¹⁶ are each hydrogen, and at least one deuterium is present; as an isolated stereoisomer or as a mixture of stereoisomers; or a pharmaceutically acceptable salt thereof; wherein the method comprises: a) reacting a compound of formula (IA):

wherein R is C₂-C₅acyl and R¹¹, R¹² and R¹³ are as defined above, with a compound of formula (IB):

wherein Q is a leaving group and R⁵, R⁶, R⁷, R⁸, R⁹ and R¹⁰ are as defined above, to form a compound of formula (IC):

wherein R is C₂-C₅acyl and R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹² and R¹³ are as defined above, under suitable conditions such that upon reaction of the compound of formula (IA) with the compound of formula (IB), the stereochemical configuration of the carbon at the 1-position of the compound of formula (IA) is retained in the compound of formula (IC); b) reducing the compound of formula (IC) under suitable conditions to form a compound of formula (I) as defined above.
 13. A method of determining the concentration of a biologically active compound in a biological matrix, wherein the method comprises contacting a compound of formula (I):

wherein: R¹ and R² are both hydrogen or are both deuterium; R³ and R⁴ are both hydrogen or are both deuterium; R⁵ and R⁶ are both hydrogen or are both deuterium; R⁷ and R⁸ are both hydrogen or are both deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; R¹¹ is hydrogen or deuterium; R¹² and R¹³ are both hydrogen or are both deuterium; and R¹⁴, R¹⁵ and R¹⁶ are each hydrogen; wherein at least one of the following applies: a) R¹ and R² are both deuterium; b) R³ and R⁴ are both deuterium; c) R⁵ and R⁶ are both deuterium; d) R⁷ and R⁸ are both deuterium; e) R⁹ is —OCD₃; f) R¹⁰ is —OCD₃; g) R¹¹ is deuterium; or h) R¹² and R¹³ are both deuterium; as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof, with a biological matrix containing a biologically active compound of formula (1):

wherein each R^(9a) and R^(10a) are independently hydroxy or methoxy; as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof; and determining the concentration of the biologically active compound in the biological matrix.
 14. A compound of formula (II):

wherein: R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R¹¹, R¹² and R¹³ are each independently hydrogen or deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; and at least one deuterium is present; as an isolated stereoisomer or as a mixture of stereoisomers; or a pharmaceutically acceptable salt thereof.
 15. The compound of claim 14 wherein: R¹ and R² are both hydrogen or are both deuterium; R³ and R⁴ are both hydrogen or are both deuterium; R⁵ and R⁶ are both hydrogen or are both deuterium; R⁷ and R⁸ are both hydrogen or are both deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; R¹¹ is hydrogen or deuterium; and R¹² and R¹³ are both hydrogen or are both deuterium.
 16. The compound of claim 14 wherein: R¹ and R² are both hydrogen or are both deuterium; R³ and R⁴ are both hydrogen or are both deuterium; R⁵ and R⁶ are both deuterium; R⁷ and R⁸ are both hydrogen or are both deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; R¹¹ is hydrogen or deuterium; and R¹² and R¹³ are both hydrogen or are both deuterium.
 17. The compound of claim 14 wherein: R¹ and R² are both hydrogen or are both deuterium; R³ and R⁴ are both hydrogen or are both deuterium; R⁵ and R⁶ are both hydrogen or are both deuterium; R⁷ and R⁸ are both deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; R¹¹ is hydrogen or deuterium; and R¹² and R¹³ are both hydrogen or are both deuterium;
 18. The compound of claim 14 wherein: R¹ and R² are both deuterium; R³ and R⁴ are both deuterium; R⁵ and R⁶ are both hydrogen or are both deuterium; R⁷ and R⁸ are both hydrogen or are both deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; R¹¹ is hydrogen or deuterium; and R¹² and R¹³ are both hydrogen or are both deuterium.
 19. The compound of claim 14 wherein: R¹ and R² are both hydrogen or are both deuterium; R³ and R⁴ are both hydrogen or are both deuterium; R⁵ and R⁶ are both hydrogen or are both deuterium; R⁷ and R⁸ are both hydrogen or are both deuterium; R⁹ is —OCD₃; R¹⁰ is hydroxy, methoxy or —OCD₃; R¹¹ is hydrogen or deuterium; and R¹² and R¹³ are both hydrogen or are both deuterium.
 20. The compound of claim 14 wherein: R¹ and R² are both hydrogen or are both deuterium; R³ and R⁴ are both hydrogen or are both deuterium; R⁵ and R⁶ are both hydrogen or are both deuterium; R⁷ and R⁸ are both hydrogen or are both deuterium; R⁹ is hydroxy, methoxy or —OCD₃; R¹⁰ is —OCD₃; R¹¹ is hydrogen or deuterium; and R¹² and R¹³ are both hydrogen or are both deuterium.
 21. The compound of claim 14 wherein: R¹ and R² are both hydrogen or are both deuterium; R³ and R⁴ are both hydrogen or are both deuterium; R⁵ and R⁶ are both hydrogen or are both deuterium; R⁷ and R⁸ are both hydrogen or are both deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; R¹¹ is deuterium; and R¹² and R¹³ are both hydrogen or are both deuterium.
 22. The compound of claim 14 wherein: R¹ and R² are both hydrogen or are both deuterium; R³ and R⁴ are both hydrogen or are both deuterium; R⁵ and R⁶ are both hydrogen or are both deuterium; R⁷ and R³ are both hydrogen or are both deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; R¹¹ is hydrogen or deuterium; and R¹² and R¹³ are both deuterium.
 23. A pharmaceutical composition comprising a pharmaceutically acceptable excipient and a compound of formula (II):

wherein: R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R¹¹, R¹² and R¹³ are each independently hydrogen or deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; and at least one deuterium is present; as an isolated stereoisomer or as a mixture of stereoisomers; or a pharmaceutically acceptable salt thereof.
 24. A method of treating arrhythmia in a human, wherein the method comprises administering to the human in need thereof a therapeutically effective amount of a compound of formula (II):

wherein: R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R¹¹, R¹² and R¹³ are each independently hydrogen or deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; and at least one deuterium is present; as an isolated stereoisomer or as a mixture of stereoisomers; or a pharmaceutically acceptable salt thereof.
 25. A method of preparing a compound of formula (II):

wherein: R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R¹¹, R¹² and R¹³ are each independently hydrogen or deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; and at least one deuterium is present; as an isolated stereoisomer or as a mixture of stereoisomers; or a pharmaceutically acceptable salt thereof; wherein the method comprises: a) reacting a compound of formula (IIA):

wherein R is C₂-C₅acyl and R¹¹, R¹² and R¹³ are as defined above, with a compound of formula (IIB):

wherein Q is a leaving group and R⁵, R⁶, R⁷, R⁸, R⁹ and R¹⁰ are as defined above, to form a compound of formula (IIC):

wherein R is C₂-C₅acyl and R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹² and R¹³ are as defined above, under suitable conditions such that upon reaction of the compound of formula (IIA) with the compound of formula (IIB), the stereochemical configuration of the carbon at the 1-position of the compound of formula (IIA) is retained in the compound of formula (IIC); b) reducing the compound of formula (IIC) under suitable conditions to form a compound of formula (II).
 26. A method of determining the concentration of a biologically active compound in a biological matrix, wherein the method comprises contacting a compound of formula (II):

wherein: R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R¹¹, R¹² and R¹³ are each independently hydrogen or deuterium; R⁹ and R¹⁰ are each independently hydroxy, methoxy or —OCD₃; and at least one deuterium is present; as an isolated stereoisomer or as a mixture of stereoisomers; or a pharmaceutically acceptable salt thereof; with a biological matrix containing a biologically active compound of formula (2):

wherein each R^(9a) and R^(10a) are independently hydroxy or methoxy; as an isolated stereoisomer or as a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof; and determining the concentration of the biologically active compound in the biological matrix. 